Alun's Viking Name Generator at Archaeoastronomy: Þorleif the Mad [That's pronounced "Thorleif"]
GORM Viking Name Converter: Ahistoricality the Peevish [That's an honor, if Anne Zook will forgive me]
The Quarter's Viking Name Generator not only gives you a name, but explains how you fit in Viking Society:
Your Viking Name is... Ásgautr Stronghorse
Your Viking Personality: You're a fearsome Viking, but you aren't completely uncivilized. The other Vikings make fun of you for that. You have a thirst for battle -- unfortunately, you're not terribly good at it. You probably know which end of a sword to hold, but you're not a fearsome fighter by any stretch of the imagination.
You might grumble a bit at the lack of amenities on board a Viking longboat, but you can handle it. Other Vikings consider you "one of the guys".
People who've known you for a while don't always trust your word. You sometimes come off as a bit of a snob. Vikings are not snobbish people -- they either like you, or they kill you. Try to be more like a Viking.