(taken from a pre-YAPC email; this may or may not be accurate. -du)
ssh 		(TCP 22)
http		(TCP 80)
https		(TCP 443)
IRC		(TCP 6666-6669)
cvsup		(TCP 5999)
cvs		(TCP 2401)
rsync		(TCP 873)
ftp		(TCP 20 and 21)
ftp-ssl		(TCP 990)
smtp		(TCP 25)
IPSec 		(UDP 500, IP Protocols 50 and 51)
imap		(TCP 143)
imap-ssl	(TCP 993)
pop3		(TCP 110)
pop3-ssl	(TCP 995)
http proxy ports (3128,8000,8080,8081)
smtp-ssl	(TCP 465)
dict		(TCP 2628)
ntp		(UDP 123)