I'm surprised no one has mentioned this yet (unless I missed it), but soy is also a complete protein, and it is available in many different forms: black soybeans for salads and chilis, tofu, tempeh, soyburgers, etc. With the current interest in "low carbohydrate/high protein" diets, I think people often go crazy and get too much protein (the average American diet has more than enough protein in it, and vegetarians and vegans--unless they go heavy on the fruits and/or junk food--get plenty of protein).
Re: rice and beans and other complimentary proteins: it was once thought (ie: Francis Moore Lappé's original version of "Diet for a Small Planet") that complimentary protein sources had to be eaten at the same time in order to function as a complete protein. It has since been shown (ie: the revised edition of "Diet for a Small Planet") that they only need to be eaten within the same day or so, as the "unmatched" amino acids are stored for sometime, and wait around to be joined by the complmentary amino acids they need in order to make a complete protein. In any case, many "complimentary protein" combinations are pretty natural, and occur in many foods: beans and rice in burritos; legumes and grains in lentil soup with pita bread, etc.
About tofu: as I believe most people who hate tofu or don't like it much are of that opinion because they may not be using it correctly, here's my tofu spiel!
First, think of tofu as a raw ingredient, much like flour or raw meat, neither of which you would use "as is." In order to make tofu more appealing, you need to use some kind of preparation method or seasoning.
There are two types of tofu, which are best for different purposes. The asceptically packaged tofu (comes in a wax-coated container that doesn't need refrigeration) is best for blending and making smooth things like puddings (add some cocoa, sweetener like maple syrup, vanilla, a pinch of salt), dips, soup bases. It is rather wretched (IMO) when used for stir fries or baking or broiling, as it has more of a "cooked egg white" texture in those situations.
For scrambled tofu (crumble tofu and add to sautéd onions, red peppers, celery,etc. and sauté a bit longer. Sprinkle in some nutritional yeast and tumeric, salt and pepper), baked tofu, broiled tofu, crumbled tofu used in lasagne, etc., use the water packed tofu that has to be refrigerated. It has a firmer texture. To make it firmer for baking, slice into 1/2 inch pieces and place them on a kitchen towel on a plate, then cover with another plate and weight it down to squeeze out excess liquid.
For an even firmer textured tofu, that soaks up marinades really well, drain the tofu and freeze. Thaw, then squeeze out excess liquid, and soak in marinade (any kind of steak sauce, stirfry sauce, etc.). YOu can use frozen/thawed/squeezed tofu crumbled in chili or spaghetti sauce, sliced and marinated and baked.
By the way, building muscle depends more on the amount of work you do (weight training) and rest (recovery which allows for building) than on eating lots of protein. So keep up a good weight training program, go heavy, vary types of workouts (a "Slow and Heavy" vs. PH, for example).