I've been a pretty big fan of Scout (ScoutApp) for this. To me, Scout's killer feature is the ease with which you can write a custom plugin. And, if that's too

I've been a pretty big fan of Scout (ScoutApp) for this. To me, Scout's killer feature is the ease with which you can write a custom plugin. And, if that's too much trouble, just use the Generic JSON URI plugin and have your code/cron/whatever dump a json file with whatever you want to track. This is quite a bit cheaper though.