for lack of a better discription, a flip flop acts like a bit of memory, from there you can do all sorts of stuff
counters
registers
dividers
???
profit
for example if you look at the logic diagram for a 74x164 shift register
(bottom of page 2) Redirect Notice
you can see its made up of 3 gates and 8 D type flip flops, your 7474 contains 2, and here is some more fun stuff to try