This article is from the Amiga FAQ, by Ignaz Kellerer with numerous contributions by others.
Of course you need to know where you find things. Many good choices are listed in this paper, as I hope. Other sources are:
*AmigaSciSchool* is a list of software and where you find it in Ascii format. It is posted monthly to the newsgroups `comp.sys.amiga.applications', `comp.unix.amiga', and `news.answers'. Additionally you will find it on Aminet sites (`text/doc/AmigaSciSchool-4.01'). It handles everything listed here and many more, for example GNU software, libraries (linked and shared), shells, Unix commands, educational and scientific software and much more.
*FishCon* are lists of the Fish disk contents. (`fish/doc/fishcon-???.lzh' on Aminet)
*FishXref* is a cross reference list of the Fish contents. (`fish/doc/fishxref-???.lzh' on Aminet) FishXref and Fishcon are in Ascii format.
*KingFisher* A Fish disk database, (`fish/doc/Kingfisher1_30.lha', which is the program and `fish/doc/KFData850.lha' ,which contains the data, on Aminet or Fish disk 863) allows search by name and context. See Fish.