I would like this topic to be a place find all the compile-time flags, environment variables, external libraries etc. which hide the patented features, like S3TC compression or floating point textures. Following is an alphabetical list of such. I would like others to post such solutions, but please restrict yourselves to completed features. If it's not ready for production use, then it's not ready to be posted here, OK?

Floating point textures:
compilation flag

S3TC compression algorithm:
libtxc_dxtn library

This is list is information resource for people living in countries, where software patents are not in force.