I get 'em constantly too. One interesting one (I think it was from Discover?) offered to take any amount up to 100k with a 2.9 or 3.9% (I forget) balance transfer charge, with the resulting balance being interest free "for life".
In other words, a front load followed by interest free. For someone my age, that could turn out to be a good deal. That 100k could turn a profit the first year in a 5 year CD and kick off ~$5k a year for doing nothing.
Next time I get one of those I need to read all of the fine print.
Edit: Ah hah...there is a catch...to get this deal you have to make two purchases per month on the card, those purchases are charged 9.9% interest, and any payments you make go against the original "0% balance" first. However I note there is no minimum purchase, so you could buy a pack of gum twice a month on the card, and pay a few pennies in interest a year on the 'gum balance'...