Reference Seforim
A. Halacha / Shas by topics - קובץ יסודות וחקירות השלם - http://hebrewbooks.org/51941
This is a great sefer. It covers hundreds of topics arranged in alphabetical order. Great for giving shiurim.
There are also two sections that catalog the shitot of Tanaim and Amoraim
Shas
A. Text of Chavruta Gemarot on all of Shas - http://daf-yomi.com/BookFilesAll.aspx?PageId=211&page=1
Chavruta is a "Shteisaltz" like running commentary on Shas with excellent footnotes. Each Massechet can be downloaded as a pdf.
B. Chashukei Chemed - A series of Sh"ut arranged according to the order of Shas (Daf by Daf). Available on Bar Ilan and Otzar HoCHochma
Collections of Piskei Halacha available online
1. שו"ת הלכה אקטואלי - http://www.shut-halacha.co.il/ (search by topic, sefer or author)
2. עולמות - http://olamot.net/shiurim (in depth pdf files on many many topics)
Likkutim / Source Books and Curricula
1. Morasha database - sourcebooks on numerous topics -http://www.morashasyllabus.com/supplement.htm
2. רץ כצבי - A series of seforim on various Halachik and Hashkafic topics. Great collection of Sh'ut approaches to a variety of questions. Very good for Shiurim on Chagim.
TaNaCH
A. Collection of articles
1. Collection of academic articles - http://lib.cet.ac.il/pages/sub.asp?item=136
TOPICS
Aveilut (Death and Dying)
A. Hakamat Matzeiva
1. On Days when Tachanun is not said. (Minchat Yitzchak 3:51)
http://hebrewbooks.org/pdfpager.aspx?req=1598&pgnum=86
B. Meit Mitzvah
1. Definition, permissible to move?, Definition of Koneh Mikomo
Aseh L'Cha Rav Vol 9:23
C. Saying Kaddish / Yizkor for first wife once remarried
1. Tzitz Eliezer 8:34
http://hebrewbooks.org/pdfpager.aspx?req=14507&st=&pgnum=224
2. מעולם ועד עולם page 223
למרות שיש הסתייגות והגבלה לאדם שלא יעלה לקבר אשתו הראשונה לאחר שנישא בשנית, וגם לא ידליק נר נשמה ביום פטירתה בפני אשתו השנייה, בהזכרת נשמות התירו. הטעם הוא כיון שעלייה לקבר והדלקת נהנר הן פומביות, ויש לאדם להתמקד בבניין ביתו הנוכחי, גם אם במידה מסוימת הדבר בא על חשבון זכרונות העבר. אבל הזכרת נשמות נאמרת ביחידות בין אדם לבוראו, ובאופן צנוע ואישי כזה היא לא אמורה להשפיע על בניין המפחה הנוכחי
Chukot HaGoyim
A. Celebrating Birthdays
1. Sh"ut Aseh L'Cha Rav (Rav Chaim David HaLevy) Vol. 4:26
Inclusion
A. 1. Wearing Teffilin over a wig (also good material on inclusion). Aseh L'Cha Rav Vol 3:3
Kriat HaTorah
A. Aliyah Breakup
1. Starting and stopping Aliyot in a "good place" - Sh"ut Aseh L'Cha Rav 4:27
B. Who can read
1. Pre Bar Mitzvah boy reading torah - Aseh L'cha Rav Vol VII:20, Mekor Chaim Hashalem 9Rav Chaim David Halevi) Vol III:123-14, Sh'ut Yechave Da'at (Rav Ovadiah Yosef) Vol II:15
Medical Halacha
A. Doctors
1. Being treated by a Doctor of a different gender
Aseh L'Cha Rav 9:27 (Also deals with no MD's, therapists etc.)
Pesach
A. Shiurim
1. Article by Rabbi Natan Slifkin on the size of a Kezayis. Lot's of great material and sources in this piece
http://www.zootorah.com/RationalistJudaism/TheEvolutionOfTtheOlive.pdf
B. Matzah
1. Shiur by Rabbi Avraham Wolfson on the meaning of Matzah -http://www.ybm.org.il/default.htm#/lesson?lesson=2560&format=H
C. Haggadah Supplements
1. Very good drasha material by Rabbi Alan Mirvis
http://www.source-rabbinic-resources.org/#!blank/lnzhp
Purim
A. Dressing up on Purim
1. May men dress up as women and vice versa on Purim? Siach Nachum (R. Rabinovitch) Siman 43; Yechaveh Daat, Vol. 5, Siman 50
B. Times for Megillah Reading
1. Earliest time to read Megillah on Purim night. Yabia Omer Vol. 1, Orach Chaim 43 (regarding Megilllah reading when their was a British curfew in Palestine); From Eretz Chemda -https://drive.google.com/file/d/0B64GDxPxJSajNWNnaWx5d0Y0YTlSbFBmQ2ZTV2F0WE9fUVdV/view?usp=sharing
C. Mishloach Manot
1. Can one send Mishloach Manot via a Gentile messenger? (Can be used for a creative shiur on using a drone or Amazon to deliver Mishloach Manot) B'Mareh Habazak Vol. II #41
http://hebrewbooks.org/pdfpager.aspx?req=43787&st=&pgnum=50
D. Sources on women and megillah reading
1. (Ta Shma booklet is forthcoming but this is a reusable source sheet) http://www.sefaria.org/sheets/2182
E. Drinking On Purim
1. Sh"ut Avnei Derech - https://drive.google.com/file/d/0B64GDxPxJSajN3dMc2FxZEFER3p1blpNcXpVN1A2VDdRN0tR/view?usp=sharing (this teshuva cites numerous sources on this issue - very good review)
Rambam
A. General
1. Introduction to Mishna Torah by Rav Yosef Kapach - English Translation - http://www.mhcny.org/pdf/Introduction%20to%20Mishneh%20Torah.pdf
Shabbat
A. Meaning of Shabbat
1. Three explanations of the purpose / meaning of Shabbat - http://www.ybm.org.il/Admin/uploaddata/LessonsFiles/Pdf/5039.pdf
B. Hachana / Kedushat Shabbat
1. Studying for tests on shabbat.
Aseh L'Cha Rav Vol. 1:36, Vol IV: 31
C. Use of Sensors on Shabbat
1. Article by Rabbi Dror Fiksler and Rabbi Eli Reiff with follow up by Rav Nachum Rabinovitch and a response b y Rabbi yisrael Rosen
http://www.puah.org.il/userfiles/file/maamarim/emounat_itecha_104.pdf (pg. 54-65, 66-68, 69-70)
2. Response by Rav Eitam Henkin HY"D, and Rabbi Fiksler and Rabbi Reiff's response
http://www.puah.org.il/userfiles/file/maamarim/emounat_itecha_105.pdf (pg. 81, pg. 86)
3. Techumin Vol 37. Full article by Rav RAbinovitch and Rav Rosen
4. Rabbi Eli Reiff on the use of swipe cards (for doors) on Shabbat
https://drive.google.com/file/d/14jEoIhYJdK5ZUNUX-2gC5eyEFZV3qlli2jZ9oHpgN1eoCkJ54awjglp4MCldS-5_dFYhM9qj7md7rCP2/view
D. Tearing Toilet Paper on Shabbat
1. Sefer Menuchat Ahava: Chapter 16:10 - footnotes 29 and 30 are very important
2. מנחת שלמה תנינא לב - Rav Shlomo Zalman Auerbach
ייר טואלט מגליל שמסומן בנקבים קטנים שערוך ומתוקן יפה מלפני השבת במדה נכונה ומדויקת והתולש משם אינו מודד כלל (מלבד איסור קורע) וללא טורח גדול הכל טוב ומדויק אף שהגמר הוא על ידי האדם ואינו דומה כלל לקוטם קיסם שכל הטורח נעשה בשבת, ולכאורה מסתבר דאין זה חשיב כמחתך'
3. Despite the above, Shmirat Shabbat Kehilchata says that he was advices by Rav Shlomo Zalman Auerbach to rule strictly in this matter.
סתמתי לאיסור על פי עצת הגרש"ז זצ"ל, שלא להכניס א"ע למחלוקת הראשונים והאחרונים בהסבר מהות מלאכת
הקורע"
This is not necc. a contradiction as he was only advised to rule strictly so as not to get involved in a machloket
4. Biur Halacha in Chapter 314 has an important position that tearing not in order to sow together (which is usually considered forbidden m’d’Rabbanan) is only forbidden when the material being used can actually be put back together again. But when that isn’t possible (as in toilet paper) it isn’t forbidden to tear at all. (Thank you Rabbi Yitzhak Ajzner)
5. See also Rav Shlomo Mesas from Volume in honor of Rav Zloti - https://drive.google.com/file/d/0B64GDxPxJSajaUFtRzNXUzJDdFU/view?usp=sharing
and Sha'ar Shimo Echad - https://drive.google.com/file/d/0B64GDxPxJSajT3JxV1haR1o2NXc/view?usp=sharing
Shiurim / Measurements for Mitzvot
A. Kezayit
1. Article by Rabbi Natan Slifkin on the size of a Kezayit. Lot's of great material and sources in this piece
http://www.zootorah.com/RationalistJudaism/TheEvolutionOfTtheOlive.pdf
Tisha B'av
A. Fasting / Observance
1. Should we still be observing 9 Av after the establishment of Medinat yisrael and the Reunification of Yerushalayim - http://www.daat.ac.il/daat/kitveyet/emunat/24/02402.htm
Teffila
A. Secular/ Church Music
1. Using Church music in shul. Aseh L'Cha Rav 3:4 (short teshuvot on various music related issues), 3:5 fascinating source offering a permissive view on the use of church music
Teffilin
A. Chatzizah
1. Wearing Teffilin over a wig (also good material on inclusion). Aseh L'Cha Rav Vol 3:3
Tevilat Keilim
A. Tevilat Keilim by a Katan (child)
1. Sh"ut Terumat Hadeshen - 257. He indicates that a child may be trained to have proper kavannah for Teveilat Keilim. http://hebrewbooks.org/pdfpager.aspx?req=14655&st=&pgnum=97
See also: Tevilat Keilim (Tzvi Cohen). Chapter 8:1; Sh"ut Avnei Derech Vol. II #4
Tzniut
A. An attempt at a modern definition and aplication by Rabbi Marc Angel
https://www.jewishideas.org/marc-d-angel/modesty-proposal-rethinking-tseniut