This article is from the Introductory Macintosh FAQ, by Elliotte Rusty Harold firstname.lastname@example.org with numerous contributions by others.
Most archives of shareware and freeware have index files
which briefly describe the various programs available at the site.
At anonymous ftp sites these files typically begin with 00 and end
with either .txt or .abs. Lists that cover the entire archive and
topical subdirectories are both available. For example if you're
looking for a program to play MOD files, ftp to sumex-aim and
look in the directory Sound/util for any files beginning with two
zeroes. You'll find 00Utility-abstracts.abs. Get it and then
browse through it at your leisure. Then when you've located a
likely candidate in the index file you can ftp it and try it out.
The best source of information about payware programs is the
MacWarehouse catalog. You'll occasionally find it on sale at
newsstands for about three dollars; but if you call MacWarehouse
at 1-800-622-6222, they'll be happy to send you one for free.
Unlike many other catalogs almost all common software is
advertised in the MacWarehouse catalog. A quick browse through
the appropriate section normally reveals several products that
fit your needs.