Facebook uses Bit.ly's services to shorten links from their site. While pages that have a username turns into "fb.me/<username>
", other links associated with Facebook turns into "on.fb.me/*****
". To you use the on.fb.me service, just use your Bit.ly account. Note that if you change the default link shortener on your Bit.ly account to j.mp from bit.ly this service won't work.