Have you tried PRTG Network Monitor? It can monitor web servers. It also has a built-in SQL database monitoring (mySQL, MS-SQL, Oracle). For SMTP/POP monitoring, you can set up a "round-trip-sensor" that sends an email via SMTP and checks whether it reaches your POP server.
I monitor a few server ports with the freeware version. For easy setup there's a nice web interface included. There, you FIRST create your servers ("devices") and THEN (on the "device") you set up the "sensors" you want.
PRTG also sends notifications when one of your servers is down. And you can see nice statistics and graphs for up to one year in the past! You see, I love it! ;-)
Maybe the freeware version is already sufficient for you. It supports 10 "sensors", which could basicly be 4 ping sensors, one email sensor, one ftp login sensor and 4 SQL query sensors or similar.
Freeware download at