SQZSoft Server Status Monitor is a cross-platform monitoring program which can monitor multiple servers and give you notifications when the servers are down.

Features:
Cross platform, support both Apple Mac OSX and Microsoft Windows
Three status for each server give you more options: UP, WARNING and DOWN
Group management makes you mange your servers easier
Real time log displaying for current monitoring operations, optional log to files

Supported OS:
Mac OSX: 10.5+, Intel 32bit
Windows: Windows XP, Windows Vista 32bit, Windows 7 32bit

Supported server monitor types:
PING
TCP
HTTP / HTTPS
FTP
POP3
SMTP
IMAP4
MySQL

Supported notification methods:
Popup alarm window
Play alarm sound
Execute specified program
Send alarm email with recent logs