I wholeheartedly disagree about not being able to bluff in the lower limits. I'm currently playing at the .05/.10 and .10/.25 tables and I'm able to pull off well executed bluffs fairly frequently. Here are some tips:

Make it look like you have some other specific card. You know when you have second pair and you check around the table the first time to feel everyone else out? Try doing it with nothing. Check around the first time and if no one bets, raise a standard amount on the turn. Alternatively, play it conservatively until a major and obvious draw card hits (i.e. a heart with 2 or more hearts on the table, the board pairing low cards, an obvious straight, etc.). One thing that's almost certainly key is to let people see you playing a winning hand or three while betting exactly the same way you're going to bluff. I've even managed to make tables scared of my min-raise (by twice in a short time holding a monster, min-raising 'til someone re-raised and then betting so much that it looked like a bluff...they call or raise me all-in and I just smile as I pile up their money...then a few hands later when I have crap and min-raise, everyone who was there for the former hands folds).

In much shorter form: it's all about building the right table image and then being able to read your table. At any limit.

- Jeffrey