You should check out that scarf that Kelly just finished in a real nice yarn - Karaoke I believe. It had a subtle color change that gave it some interest but wasn't too girly. Here's the link to her FO thread.
I was just gonna suggest that, Ben! Thanks! Knitting a manly scarf has ALOT to do with the yarn you use. And, I think a simpler pattern is best. The scrunchable pattern (you can find it on Ingy's link) is nice because its soft and warm. And not too plain. You can "girl it up" by adding a crochet border on the ends, or leave it plain for a manly lo0ok.
I made my son an Irish Hiking Scarf (In the patterns section of KH or scarf section of KnittingPatternsCentral). It's very manly and simple to do. I used Wool-Ease and it was a nice weight and very warm.