This will take you to David's Page
Ran into this one recently related to the Meeus Julian day algorithm, proof of correctness
The home of ZLIB (zip library)
Current stuff for Internet Config
I had the need, on-call support, to locate a OS X solution this week.
The best general reference page I found
OS X tn3270 beta the one I found to use. Appeared usable but haven't actually tried it. The company provided prior was tn3270 for OS 9.
I didn't notice a open source free java version anywhere. Although a few java commercial offerings