I recently acquired what can only be described as a real shed of a single speed. It's an ugly bloody thing but I have kind of fallen for it's ugly charms. It's like that ugly person you never thought you'd be attracted to, only to find yourself marrying them and having 5 ugly kids with. Anyhoo I'm having a few problems with it at the moment, mostly being the back brake and the bottom bracket.
The rear brake is refusing the touch the rim correctly, and will rub the tyre if it's used. I've adjusted it best I can but it's still being an ass. Will keep plugging with it! It's worth the effort because the bike's so responsive.