ah, acid_kewpie, it could be related to networking.

Most of the software in this category is thought of as network monitoring software. If the question had been posed that way . . .
Anyway, most of this sort of software does email notification. There are a number referenced here:
http://www.linuxquestions.org/bookmarks/tags/monitoring . Although my favorites are not.
I really, really like mon. It is the ultimate simple, direct, extensible tool. You can find it at
http://mon.wiki.kernel.org/index.php/Main_Page . You can also check out a blog posting I wrote about mon here:
http://blogs.umass.edu/choogend/2007...nitoring-tool/ .
For watching log files and identifying error conditions, there is SEC (Simple Event Correlator), which, again, is a simple, direct, extensible tool. It can be found here:
http://www.estpak.ee/~risto/sec/ , and, if you couple it with syslogng, you can centralize your logging and have SEC watch them all as well as catching patterns across the network. Syslogng can be found here:
http://www.balabit.com/network-secur...ogging-system/ .
Another thing to think about is what happens if your email or network connection goes down? Then there is no notification. Having more than one monitor, and having other notification avenues, gives you fail safes and fall backs. Maybe an analog line and paging or text messaging, or some method to pop up an alert on your desktop from the server.
All of this is probably more than you thought you were asking for, but it is a complex and competitive area with lots of open source and commercial software offerings.