My tank has the following:
3" Red Eared Slider
2 3" Gold Gouramis
2 3" Chinese Algae eaters
1 4" Red-tailed shark
The turtle snapped at the fish a couple of times when I first put them in, but after a while she got used to them and now leaves them alone. She will snap at any new occupants, however, and will eat whatever she can fit down her throat. We used to feed her toughies once or twice a month, but have stopped feeding her live food since co-habitating with fish.
I think your chances of sucessfully putting fish and turtles together is higher if you introduce the fish when the turtle is very young. That way she gets used to them as part of her habitat, rather than food.
I think it is a great combination. The algae eaters hide most of the time, the shark keeps to himself (and chases anything out of his cave, including the turtle), and the gouramis are so bold as to try and steal pellets from the turtle when she's eating!
This all being said, I did loose several fish to my turtle until I figured everything out.