If you have mighty claws, like me, I use my nails to pry the battery out like Carrion4worm and Dustin69 mentioned.
However a simple solution I've applied to friend's batteries is to loop some invisible/magic tape around the battery, and cutting them so there are 2x1cm tabs at each end, with the two sticky ends stuck together to create a 1cm tab you can use to pull the battery out with.
If it doesn't work how you'd like, it's easy enough to remove the tape with minimal mess and it's inexpensive.

I'll make one now to show you what I mean:

I don't like smacking mods because it risks damaging the internals.