Did you know that you don't have to drain your tofu for hours and marinate it overnight in order to get satisfying grilled tofu? Oh it's a fine technique and still probably the best way to really infuse your tofu with flavor, but if you haven't planned ahead, you can still get delicious grilled tofu on the dinner table with very little effort. You're gonna need -
a grill pan
a block of tofu (the firmer the better, but softer tofu will just take longer to cook)
about a cup of bbq sauce
basting brush or teaspoon if you don't have a brush
cooking spray
The idea here is that you're going to cook the tofu over low heat for a long time while you periodically baste it with sauce. In this way, the moisture will gradually dry up (replacing the draining-on-paper-towels-under-a-pot-weighted-down-with-a-bag-of-rice step). And the sauce will have time to soak in. I put the tofu on the grill first thing while I ready the remainder of the meal, in this case while I made mac n' cheese and salad. It can cook on medium-low for a good long time. Any time you walk past it, baste it again with the undiluted (You don't want to be adding water back to the tofu.) sauce. Flip it every once and a while so that it's cooking evenly and getting basted on both sides for maximum flavor absorption. I flip it after every couple of bastes and probably wind up flipping it about 4 times in all. When the texture of the tofu has gotten firmer, when it has nice grill marks and carmelizy saucy bits, it's done.