Pair programming is awesome.

We tried it at one company I worked for and being able to put two minds together gives you a much broader knowledge base, and having someone over your shoulder as you code forces you to be more critical of what you code. You catch things so much easier. Wish we were still doing it at my present company.

I also agree with hot_ice - documentation is soooo necessary! Ever go back and look at code you wrote a year prior and think - "What the heck was I trying to do here???"

And you're thinking this while looking at code you YOURSELF wrote. Imagine going another step back and reading someone ELSE'S undocumented code.