I often run into aggadic passages in the Talmud, and would like to get a list of references beyond the standard 4 (Ein Yaakov, Maharsha, Benayahu/Ben Yehoyada and the Chiddushei Aggados of the Maharal).
Is there any other reference, which would interpret aggada, preferably not al-pi derech pshat?
Thank you very much.
Among Rishonim, the Meiri often explains aggadah, and the Rashba wrote a commentary specifically on aggadeta. The sefer Ein Eliyahu is a multi-volume commentary on aggadah. Many aggadeta are also discussed by the Chida in his פתח עינים. R. Moshe Tzuriel also collected many commentaries on aggadah in his Leket Peirushei Aggadah. The encyclopedia Aspaklaria, which is available online, contains alphabetical entries for aggadic topics, and sources from Chazal, rishonim, acharonim, sifrei chassidus, and mussar. The Mesivta and Artscroll gemaros also contain helpful references (Mesivta has a section specifically on the aggadah; in addition, Artscroll is now publishing the Ein Yaakov with expanded commentary).
See also this article, especially n. 10.
Many of the answers already given are excellent. So I will simply add some additional resources that you might find useful. First of all, there are the following two seforim on aggados that were not mentioned yet:
R' Yakov of Lissa (author of the Nesivos HaMishpat) wrote a commentary on Aggados titled Emes L'Yakov.
R' Yosef Shaul Nathansohn (author of the Shu"t Shoel U'Meishiv) wrote a commentary on Aggados titled Divrei Shaul.
In general, however, the main place you find in depth discussions of aggados is in the classic sifrei drashos. Many of these works are now printed with indexes which can enable you to quickly find any discussion of a specific passage. Among the most prominent of such works (including some personal favorites) are:
Sefer Parshas Derachim by R' Yehuda Rosanes (the Mishneh L'Melech)
Sefer Bina L'Itim by R' Azaria Figo (the hebrewbooks.org edition is almost unreadable)
Sefer Olelos Efriam by R' Ephraim of Luntschich (the Kli Yakar)
Sefer Michtav M'Eliyahu from R' Dessler (the fourth volume has a comprehensive index).
There are of course, many, many more such works. Some of the other answers have mentioned recent works that have attempted to help one find these materials, however, there remains a great deal of material that has yet to be generally indexed.
There is a book that you might enjoy, titled פירוש על כמה אגדות, which was first published by descendants of the Gra in Vilna, 1800. It comprises the Gra's commentary on the Rabbah bar Bar-Chanah stories (Bava Batra 73a-74a) and the Savei deVei Atuna riddles ("the riddles of the elders of Athens"; Bechorot 8b, Avodah Zarah 11b and Yoma 9b). It has been published in a bilingual version, with the original Hebrew in the back and an English translation in the front by Aharon Feldman, and is titled The Juggler and the King: An Elaboration of the Vilna Gaon's Interpretation of the Hidden Wisdom of the Sages (Jerusalem: Feldheim, 1990). The publication also includes the English translation of an essay by the Ramchal on the nature of aggadic passages, first published as an addendum to his Derekh haShem.
You might be interested in the index and collection of commentaries on Agadot, found on the Mechon Halacha Berura's website. I didn't fully understand the relationship between the Halacha Berura Institute and this collection of commentaries on the Agadot, but either way, they collect explanations of Agadot that are scattered throughout, Rabinical Literature.
For example, here is the index of commentaries they collected on Talmud Berachot (sorted by Daf), and here is the full text of those commentaries.
Here is the list of Sources they used when making this collection, including links to many of the Sefarim that are available for download.
You would probably like this JLI class called Curious Tales of the Talmud: Finding Personal Meaning in the Legends of our Sages. See if you can find one in your area.
Especially the book that comes with the class has many references to Aggadas, and by seeing which books are quoted you will probably find many leads.
You are unlikely to find any which are directly on the gemoro. Instead use a mesivta gemoro which brings from many seforim that talk about the agados, although these seforim are not based directly on the gemoro. My understanding of the question is that 'he runs into difficult passages' meaning he wants a sefer which will provide him with any he 'runs into'. My answer provides that. The other answers will have a very, very limited amount of aggadot he is likely to run into that they discuss.
I'm glad to see that many have already provided useful answers to this question. I can second the recommendations for the Divrei Shaul and the fantastic collection on Halacha Brura. If the passage in question refers to a verse in Torah, you can see if the Torah Temimah cites the aggada and see what he has to say in the footnotes.
Not mentioned above are the two volumes of HaMafteach by Moshe Schatzkes. (This is NOT the same Moshe Schatzkes of Lomza who was RY at RIETS in the post-war era.) The first volume (of two) is available online. I am not familiar with these volumes, so I don't know how useful they will be for you.
Finally, you'll find many interpretations dispersed amongst other works not necessarily dedicated to aggadeta. To find some of them, do a search of hebrewbooks.org using a two or three word phrase from the aggada in question.
Another one is the peirush of the Maharal on many Aggadeta. It is printed in separate volumes, but is part of larger sets of his works.
And also, the sefer Darash Moshe by R' Moshe Feinstein zt"l has many fascinating explanations of perplexing Aggadeta Gemaros.
