Mini pumps

Zefal standard pump from Evans, 4.99, much better than any mini I've tried, gets up to 90 psi. At about 55cm it fits into any bag and you will of course have your track pump at home to get up to 120. Mini pumps are rubbish, frustrating and unneccessary.

Topeak Mini-morph is a fucking great pump and can get you up to 120psi without many problems. Well designed little thing too. Alternatively the full size one (which is still a mini pump really) the Topeak Road Morph is just as good but gives you a little more power due to the longer barrel... so basically if you want to spend £25+, mini pumps aren't rubbish.

And if you are riding without a bag?

Most fit in jersey pockets.