zap2it.com (boy have they grown up since the last time I checked them out!) used to charge a nominal fee for local guide listings, and they offered a full blown API for accessing them. I believe Microsoft even licensed it for their Windows Media Center TV listings. I can't seem to find any information on their site anymore, though... :? This URL found via Google would seem to suggest it still exists...
http://api.zap2it.com/channelfinder/versus/
My Channels: http://roku.permanence.com - Twitter: @TheEndlessDev
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