This is actually a big question. You might like the discussions on the mac sci tech mailing list. Have you considered gnu plot? Cricket was great.

I've started the imap service, but I can't get mail. I suspect it's because port 143 is blocked. From my cube:

ip68-8-199-89.sd.sd.cox.net:~:1%telnet sugarcube.homeunix.net 143
Trying...