I am the owner of a home in Maryland. I have a roommate I took in temporarily due to tragedy in his family. Well it has been going on 3 years now, dude ain't working still, and he is now of the taking it all for granted mode of operandi. He was a dear friend, I stress was... I want him out, what is my legal recourse?

I assume there is no lease and this "friend" is not paying rent - correct?

You start by giving him written notice that he is to vacate the premises within the next 30 days. If he is not out after 30 days you then start the process to obtain a court order for his eviction. That court order then will cause the sherriff to come and forcibly remove him if he has not moved out. Here's a link with some helpful info for MD:
District Court of Maryland - Landlord/Tenant Issues (http://www.courts.state.md.us/district/forms/civil/dccv082br.html#refusestoleave)

Of course this can get messy, and given that this is your personal home it may not be too pleasant. So before going the legal route - have you talked with him, does he know he has overstayed his welcome?

... taking it all for granted mode of operandi...

Mixing languages in the same phrase is, er. gauche.

The word "mode" being an English word and "operandi" being (Law) Latin.

I think "modus operandi" is the phrase for which you are looking.