The Internet is a wonderful thing. 18 months ago I wondered why there wasn't a service where you could upload photos that you'd taken whilst watching a marathon or some other race. Turns out there is, and it's 3 years old today, much predating my musings.
You can find them at 42run.com. All you need, if you're a runner, is your bib number - you can then search against all races they've covered.