I just finished reading "Effective C#: 50 specific ways to improve your C#" by Bill Wagner. Definitely worth a read. Not too long, and each point is only several pages so you can just read a bit and put it away, read a bit and put it away, read a bit, and - you get the picture.
I've started Refactoring by Martin Fowler. Seems like another great book.
I really wish I'd started reading these much earlier in my career. Although I'm finding that a lot of what I'm reading I'd already picked up from other sources, but it's nice to read a comprehensive coverage of each topic.