How to align a chain on a single speed My bicycle currently has poor chainring/rear sprocket alignment (as in the chain at the front is more than a chain's width from the chain at the rear). I'm wondering what the procedure is to correct this alignment, because currently riding the bike damages the chain. (I have already moved the wheel as far across as i can using washers)
To adjust chainline, you can:

At the back


use spacers between the hub and cog


At the front


use a longer/shorter bb spindle (as Kibbee says)
use spacers on the bb cups (as Mark W says)
use chainring washers (and likely different bolts) to adjust the position of the chainring on the crank


I'm struggling to think of any more options. 

The only other thing I could think of is that if you do end up with an imperfect chainline, despite your every effort, then a 3/32" chain will be more forgiving than a 1/8" chain. 3/32" chains are designed to be able to traverse cassettes so have a little more flexibility in them.