Does anyone know of any tools for tracking application usage?

I.e. when someone runs an application the usage of which you wish to monitor a note of this is made somewhere. From these notes is is possible to obtain information such as how many people have used that application, when it was most recently used, maybe produce a pretty graph showing how many times the application was used each month for the last X months, or other useful information. This information could be used to aid decisions such as whether to renew a license for an application.

I've not been able to find anything like this, though maybe I've just been using the wrong search terms.

I think I have a good idea on how to write such a thing myself, (using a syslogd server, a simple wrapper script to launch the relevant applications and some scripting to parse the resulting syslogd file for use in a web page), but if a suitable solution exists already then that would save me some effort.

Have a look at splunk

Also if looking to rrdtool-based graph then check cacti.