Firefox : A great free web browser without catastrophic bugs or scary security holes as some other browsers out there.
Thunderbird : The companion e-mail program for Firefox. No ActiveX issues with this one.
Miranda IM : A multi-protocol instant messenger client for Windows. Recommended by havdi, a GeoShell user.
putty : Recommended by Pistos, a GeoShell user, who said, "*The* telnet/ssh client."
Netlab : NetLab is a multithreaded Windows 95/98/NT 4.0 program that has features including Finger, Ping, Whois, Traceroute, DNS and Time Server services. Does not work on 2K, but might work in XP using the compatibility mode option for Win 98/ME. (PS, I love archive.org! - see Interesting Sites section)
Digsby : I use this at work. It's a multiprotocol instant messaging client. Has a lot of features I don't use (email, social networking), but is much better than the previous client I was using.