Maybe... Make it so that you need to collect lava from a source block, but when placing it it will place a non-source block? Lets you keep the ability to get buckets of lava for the furnace without being able to get infinite lava or being able to set up easy infinite cobblestone generators.

Ok, finally decided to register on here rather than just lurk as a guest, because I wanted to point out that one of the big reasons FC has stated he doesn't want anyone else distributing BTW is because he wants to make sure people are able to get the latest version. This link doesn't go to the most ...