Just a small note, FairwayMapper.com has made available a pool of Overpass API slots to our own load balanced overpass infrastructure as a bit of a thank you to the OSM community. I am mildly pondering opening registration for a paid for service but thats just curiosity on my part at the moment.
Details available at FairwayMapper (note that you require 20 OSM changesets in the last 90 days to be eligible - and keys expire to free slots up if not used in the last 30 days).