I love the 6 max tables. Most players at the lower limit 6 max are eager for action and mostly pretty loose. On an average day if you play tight aggressive you make a good profit. I only play lowere limits like 2 4 and 3 6 because as you said the blinds can eat you up at the higher limits.
I dont know of any books specific to shorthanded play, but there are references in super system. Mainly it says to play a little looser. Howard lederer said he plays a 6 max table like he does a full table. Meaning If your first to act at a 6 max table youre really in middle position at a full table. If that makes sense. So really you can play your middle position cards at a full table the same as if you were first to act on a 6 max table.
As regards to sites, I find the sites that have alot of european plays like interpoker and noble poker the loosest, and most profitable.