Right now I have two pairs of shoes that I mainly use--New Balance 800 Midfoots and New Balance 904s. I also have a pair of Saucony ProGrids that I wear but they're getting near 500 miles on them. I also have screws drilled into the bottom for snow & ice traction so obviously I don't use them on the treadmill. I also have a pair of Adidas racing flats but they're not so handy for wintertime.
Lately I've been doing a lot of reading on running shoes and there's some pretty interesting questions out there, though not a lot of answers. Is barefoot running "better" than running in shoes? Do running shoes actually cause injuries?
I just finished reading Born to Run and last summer I read ChiRunning. These books, along with various articles online, made me think more and more about going with the least amount of shoe I can get away with. I don't buy into everything ChiRunning and Born to Run have to say about running technique and minimalist footwear, but I do think there's something there.
Though there's some questionable information and advice in ChiRunning, I do like what Dreyer had to say about gradual progress. Basically he says to slowly move toward a more minimalist shoe rather than throwing out motion control trainers and jumping into ultra light racing flats. Eventually I'd like to be able to wear mainly racing flats and if I get brave enough I'll even get a pair of Vibram 5 Fingers. I also plan to incorporate some barefoot running into my training once the weather starts getting warmer.