I've been a fan of RescueTime for a while. I periodically like to take a look at how I spend my time and Rescue Time does a great job at giving me access to some great data.
Since I'm running Ubuntu as my OS and there is no native uploader, I'm using the RescueTime Linux Uploader.
Just following the provided instructions however leaves some things not working. Primarily the applets don't work.
To get around that I found my answer in a Ubundance blog post.
Basically I had to create symlinks to the default installed programs which end up in /usr/local/bin back to /usr/bin and everything worked.
So once you have the RescueTime Linux Uploader installed just run:
sudo ln -s /usr/local/bin/rescue* /usr/bin/
and everything worked well.
The original blog post just does an ln, but the symbolic links are working for me.