22.2 is, I believe, an old English size. I had a set of chrome bars and stem on a 60's Raleigh which had no bulge in the centre of the bars. I don't recall the measurement, but it was considerably smaller than 25.4

Just checked on Sheldons site, and the bars I had were probably 23.8! 22.2 is the BMX handlebar standard, and older MTB's had them too. I think that if you buy ape hangers and so on, they tend to come in this size. It looks like .883 is also the BMX standard. Just goes to show there's more out there than we think! See here for details.

http://sheldonbrown.com/gloss_st-z.html#stem