As mentioned the Zebralight's are great, which model depends on what battery's you want to use and how much your willing to spend. Right now it's hard to suggest anything less than a Zebralight SC600 because it's such a great utility light (low is low and high is extremely high), it uses a 18650 Li-Ion rechargeable battery. The SC600 is around 4.2" long and is easily pocket-able, it's low is .1 lumen all the way up to 750 lumens, it really depends how much you want to invest in it.
If you don't want to vest that much into it then the SC51 is a great choice as well, as already mentioned.
If you don't want to vest that much into it then the SC51 is a great choice as well, as already mentioned.
