I wouldn't say I'm my daughter's friend as such, I am most definitely in charge not that she always listens, but I have fun with her, rather than just taking her to fun places, or to do fun things like my parents did.
Eg, my parents would watch my brother and I swimming at a great new pool or take us to a theme park and let us go on the rides while they watched, let us listen to music we liked etc, but they'd never join in, or really take an interest.
Once we were old enough to go alone, or they could leave us somewhere, then that's what happened.
Not only am I a younger parent than what mine were, I'm much more fun, and a big kid myself really, I'll play Polly Pockets, or take turns on the DS with DD, share turns on her scooter, dance around to music she/I like, took her to X-Factor live which was for me too really, trolley surf in the supermarket.
I'd like to be her friend when she's grown up and I feel I need to do the groundwork for this now, well since always really.