What is “?nomo=true” ?

Google Webmaster Tools is showing that I have many duplicate meta descriptions on my site. Most of them are my URLs with ?nomo=true tagged onto the end.

For example: http://completerunning.com/?nomo=true

I have no idea what these are. I suspect it *may* be something left over from when I was hacked last year (I believe my site is all cleaned up now). Go easy on me – I was sick when it happened. 🙂

Any ideas? Thanks very much.