The time comes in every geo hackers life when he or she will need to do reverse geocoding - that is, convert latitude and longitude to a street address. And when this time comes, the only resource you'll need is freereversegeo.com. They offer a trivial API to slurp in a latitude and longitude and give you back surprisingly accurate data.
Say you want to know the real address of 38.898563° latitude, -77.037223° longitude? Plug those coordinates into their API and you'll get:
The XML based API couldn't be easier to use. And if that weren't enough to convince you that this is a site worth holding on to, check out the commercial licensing policy:
Commercial licenses cost only around $5 per year, per company for all you can eat.
What a deal. Hold onto this site. You'll need it one day.