WAN Check automatically checks to see if your Internet connection is still active. If it isn't, it alerts you with a message. You can also let it notify you if you are reconnected to the internet.
The WAN Check daemon runs as a background process, so you will only see it in the OS X Activity Monitor.

Version 2.2.3:

• Reset utility included to fix some bugs with old pref files
• Display note to notify you that the 'wancheckd' started
• Optimized code a bit
• Error handling bug fixes
• E-mail notifications!
• Event logs written to /Library/Logs!
• Fixed version update alert bug
• Ability to turn update check on/off

Requirements

Mac OS X 10.2 or later

*Previously available here