This is my commuter bike. And my excersise bike. And my road bike. And my trail bike.
I need to get a bike better suited for commuting, but until I can afford that, this'll do. She's a 2004 Cannondale F300, a gift to myself for my 30th birthday two years ago (The place where I lived at the time was right across the street from 36 miles of pipeline trails, very very sweet). It might not seem like much, but its the 'fanciest' bike I've ever owned.
The only changes to it are the pedals and a stem extender for the handlebars (I slipped a disk a month ago and I'm doing what I can to ease the strain on my back and neck). The rear rack and panniers I bought at a local store. They're simple, water resistant (not water proof, but that's alright). They hold my days clothes, lunch, and emergency stuff.
You can't see it, but it does have a reflector in the back, though I'm planning on getting some blinkies. In the meanwhile, I either wear a reflective vest (I actually got it while biking through areas where hunters are.) or an extremly bright yellow biking top. Cars see me
It's an 17 mile round trip ride to work, pretty much all on roads, except for a one mile stretch of bike trail and another mile stretch of sidewalk (which is the prefered method over a round with 55 mph and no shoulders. Much safer

)