Here are some basic Q2 Files:

Quake II 3.20 patch		- Patch from 3.12 or higher
The NEW Outlands map		- A more balanced version of the Outlands map.  (q2ctf4a)
Q2PLUG		- Allows you to 'see' and join Quake 2 servers from your browser.
area51 essential Q2 files		- alternate download locations for these files, Action Quake files, and CTF.  Everything you need to play online!

Action Quake models/skins come with the AQ client pak.
Links to all the latest essential AQ files at area51.

CrackWhore		Visit the CrackWhore files for more skins and screen shots of CW in action
Q2PMP		The place to find all the Q2 models and skins you could ever want!

WC WinAmp Skin		Designed by Hirudin for you MP3 lovers.
Mouserate / Jamie Hankins (NT,95,98)		For an explanation of what these files do,
Qizmo / Juha Kujala (95,98)		read Jazz's news update about them.