I was reading the MS Exchange team blog and came across this interesting Microsoft site that I wasnt aware existed.
Have you ever thought 'why does the x feature in Word work like that?' or 'why can get make Exchange do x?' then its well worth spending a few minutes taking a look at the Usability Research website and sign yourself up.
An excellent oppotunity to shape the products you use everyday and you might even be able to lay claim to your own feature in the next generation of Microsoft applications!