[JeremiahMN]

zabbix will do all of this for you....

It's not my favorite tool, but it is free and open source.

[forkie]

Zabbix is hard to configure. Need something easier.

[duskos]

I'm using Check_MK as a full scale monitoring solution. It is big and powerful, but configuration is pretty straight-forward with its Web Administration Tool. It will happily monitor single service or big bunch of services.