Typical services running on ports: (0-65,535 | 16-bit number/2 bytes)
Well Known - 0-1023
Registered - 1024-49151
Dynamic/Private - 49152-65535

20 FTP (data) (TCP)
21 FTP (control) (TCP)
22 SSH
23 Telnet (TCP)
25 SMTP (TCP)
49 TACACS
53 DNS  (TCP/UDP)
67 BOOTP server (UDP)
68 BOOTP client (UDP)
69 TFTP (UDP)
80 HTTP (TCP)
110 POP3 (TCP)
119 NNTP (TCP)
123 NTP (UDP)
137 NetBIOS name service
138 NetBIOS datagram service
139 NetBIOS session service
161 SNMP (UDP)
443 HTTPS (SSL) (TCP)
1311 Dell OpenManage
3306 MySQL
3260 iSCSI
3389 Remote Desktop Protocol
3724 World of Warcraft
4000 Diablo2
5900 VNC (for Windows)
5901 VNC (for Unix)
6112 Starcraft
6346 Gnutella
6348 Gnutella
6881 BitTorrrent
16567 Battlefield 2