I built a real estate site that ingests data from the local MLS for the newspaper I work at. and noticed today an additional charge on the bill from the MLS.. It was labeled.. "NAR / CIVIX Settlement" after doing a bit of research it seems that CIVIX holds a patent on the ability to do searches for things like businesses around a geographical area.. Reading the actual patent makes it sound like just about any web app that we (and other web developers) can build would be infringing on the letter of their patent... Have you heard of CIVIX?..
On one hand, I'm totally in favour of patents because they protect the inventor of very useful things. Like, the person who invented GIF compression SHOULD be rich. And whoever came up with the ideas for SQL and LDAP and SOAP and contextual ads and so on, they all deserve a pile of cash.
OTOH, developing anything for the Internet, since early patentgrabbers were able to patent the most absurdly generic ideas, is a minefield.
Some might call it a rite of passage for a successful business. When you get successful enough, all your innocuous patent infringements detonate. How nice that MLS is passing the settlement cost down to their data subscribers. </sarcasm>