Ok, so for serious work I have the big, heavy, full frame Nikon D3. Which is in turn slowly being edged out by the tiny GH2. But here we have everything you need for serious photography, provided the subject isn't running around too fast. Olympus E-PM1, 12mm f2, and 45mm f1.8. Takes up three pockets, and I can convert myself from biker to photographer in moments.
Really very highly recommended!