I made a useful toolbar that I thought I'd share here. It's called the "Little Black Bar" and the idea is to share notes about online dating profiles as you're browsing them on a dating site. For example, if a person doesn't return calls or their pictures are way out of date, you can leave a note through this toolbar and others will see that note so they don't waste their time.
You can get the toolbar here: http://littleblackbar.com
As an added bonus, it'll also try to look up the Twitter and Facebook profiles of the profile you're looking at. It currently works on match, pof and okcupid.
Please feel free to feedback if you think this is useful, and ideas to improve it would be great. The toolbar is 100% free.