[mih]

I second Manic Time. It's offline, so your data remains with you. Plus in addition to graph visualizations, it also allows you to track what applications, documents and websites you spend most time on.I reckon they have a portable version of it too.

[riprock]

my problem with these tracking apps is that it's too easy to "cheat" the system if you have more than one monitor. I typically have a video or stream open on one monitor while I have focus on a window in another monitor so the app doesn't log my distractions.