From AdminWiki

http

• Apache httpd - the swiss army kitchen
• lighttpd - lightweight singlethreaded/singleprocess webserver. ideal for pushing large amounts of traffic.

ftp

• ProFTPD
• vsftpd

smtp

Daemons

• Exim
• Postfix

Blacklists

The bane of every administrator.

• openrbl

imap / pop3 / mail access

• Dovecot
• Courier
• CommuniGatePro (Commercial)

File Sharing

• CIFS and Samba
• NFS

ident

ntp

• ISC ntpd
• openntpd
• xntpd

The NTP Server pool exists which you could use, but shouldn't on production-class systems. Better query one of these reliable stratum 1 and 2 servers instead:

• ntp1.BelWue.de
• time1.euro.apple.com
• ntp1-rz.rrze.uni-erlangen.de
• ntp1.ptb.de
• time.nist.gov
• time1.stupi.se
• ntp0.nl.net
• ntp1.ien.it
• swisstime.ethz.ch
• clock.nc.fukuoka-u.ac.jp
• tock.usno.navy.mil
• bigben.cac.washington.edu
• nist1.symmetricom.com
• Tick.UH.EDU