Knee issues (patellar-femoral syndrome initially diagnosed in summer of 2007) sent me down a path of re-evaluating the active side of my life... I have fully converted to minimalist footwear and when warm enough (and not dark out), barefoot running. Running in a minimalist shoe has gotten me back into running and I enjoy it for the first time in my life. Running in a minimalist shoe retrained me how to run with the correct form and now I know how terrible my form used to be. I used to be a heavy heel striker, so it's now wonder I've always had some sort of knee, ankle or hip issue.
My minimalist shoe line-up started off with VFF KSO's (Oct 2009) and then I added Feelmax Kuuva Boots (Dec 2009), Feelmax Osmas (Feb 2010), Terra Plana Oaks (Dec 2010) and recently won a pair of Vivobarefoot Neos (or Evos depending on availability) through Donald's Running and Rambling blog. I love testing out new shoes and have pretty completely only wear a minimalist shoe whenever possible.
I do have a pair of Inov-8 295s (Almost 3 years old and ready to retire) and recently purchased a pair of New Balance MT 101's. These don't fall under my definition of minimalist (however, they are minimalist compared to the majority of running shoes used by the general population), but have worked well for me for trail running, running in snow and hiking/backpacking. The elevated heal of these trail runners doesn't seem to affect my gait too much on an uneven surface like trails and snow.
But alas, my new enthusiasm with running caused me to overtrain for a 25k trail race last spring and since then have been wrestling with IT Band issues. After much research and testing to keep it from flairing up, my plan for my training will now consist of 1 long run per week and cross-training (core exercises, hiking, biking, weight-training, etc.) I've also found that the slow-to-medium pace running seems to irritate my knee the most, so I've adopted a modified Fartlek method of running. It seems that my knee doesn't seem to bother me when I run fast and it doesn't bother me when I walk. So after I warm up, I run hard and then power walk (to catch my breath), run hard and then power walk, repeat, repeat.... This seems to be the ticket for now and maybe at some point I can reintroduce longer runs with consistent slower running. This and icing my knee after every run seems to be the key to keeping the knee from flaring up from the IT Band irritating it.