I mostly ignore free stuff on the web. I know a lot of people produce content for free, but I've got a mental block - if nobody's charging money for it, how valuable can it be? In general you get what you pay for.
I saw a mention of the Classic Dungeon Designer's Netbook #4 on K&KA, checked it out, and was just astounded. Presumably everybody but me already knows about it, but wow. Table, after table, after table. This is about as useful as a supplement can get.
So sometimes free stuff is awesome.