Good base -- made changes
I've made this recipe before with different meat and vegetable combinations, but they always came out somewhat soggy and spongy. Finally, after more tinkering, my last batch came out perfect!
I took the advice of other posters to reduce the milk to 1/2 cup, to cook the vegetables prior to sticking them in the tins (to get the water out), and to cook the quiches for 40-45 minutes instead of 25. I also found a tip online about helping mini quiches not stick to the pan: line the bottoms of the muffin tins with a pinch of cheese rather than mixing the cheese in with the eggs. This might mean increasing the amount of cheese to a little under half a cup, but it also means that the fat in the cheese forms a crust around the bottom of the quiche, keeping it from sticking in a non-stick pan (I didn't even spray my tins!) and creating a crunchy rather than a spongy bottom.
Lots of others have commented about trying out different combinations of meat and cheeses. This is what I used this time around, and it turned out really nice: lowfat mozzarella (just under 1/2 cup), 4 oz. (instead of 8) lowfat chicken deli meat, 1 large shallot, 2 medium tomatoes (insides scooped out), and a small handful of fresh basil.
What other combinations have you all tried? Now that I've finally figured out how to do these right, I want to make them more often!