said by Kearnstd:(on a side note its easy to remember which does make it an excellent choice from a business perspective.)
They also have morrisonfoerster.com that redirects to mofo.com. However, shortness and being easy to remember is important, but my guess is that it's more to prevent confusion. I'm presuming that foerster is pronounced like forester and if they only used the morrisonfoerster.com names, a lot of traffic and email would inadvertently go to morrisonforester.com instead. By using mofo.com, that whole issue is avoided.