Hmmm, recommend a piece of software to install by compiling it.
That would depend on what you want to do. Any application you see from Slackbuilds that you might want would be a good candidate, and Slackbuilds conveniently lists the dependencies.
Hmmmm, how complicated do you want to go?
If you are looking to do some webdesign, how about Kompozer
If you want to learn about dependencies, Audacity
. They both have a lot.
Edit: Oh, yeah, bookmark the Slackbook
. It's somewhat dated but still mostly accurate.