Macaroni and cheese is a staple for starving college students - at less than a dollar per box, these cheesy noodles are a cheap way to get a meal in.  However, after a while, the taste can get more and more plain.  Here are a few ways to spice up that classic box of Mac n' Cheese.

-Add extra cheese - real cheese, not the cheese packets.  Keep a brick of cheap cheddar, mozzarella, or evenVelveeta in the fridge, and toss a few slices into the pot.  It makes it stickier and more cheesy.
-Toss a (drained) can of tuna into the pot once the noodles are good n' cheesy.  Stir well.  It might seem to be a bit too casserole-y, but it's a cheap and easy way to put some variety into it, and it's not bad to boot.
-Chop up a couple of hotdogs and toss them in, as well.  (Thanks for reminding me, Tem42!)
-Put some green beans in there.  Again, it seems to resemble a casserole, but it's pretty tasty and it's a good way to stick those veggies in there without having to taste them too much. (Tem42 recommends peas instead of beans.)
-Chili powder (or any other spicy spice, such as cayenne or strong paprika or cumin) will really kick up the flavor - but be careful not to use too much, or it'll overshadow the delicate flavor of the cheese.
-Similarly, experiment with just about everything in the cheap spice aisle at the local supermarket.  Oregano, basil, garlic powder, even lemon pepper will do.  It's all based on your personal taste.  The one thing I wouldn't recommend is blending in too many different spices at once - one should be enough, and three is pushing it.
-Replace the milk in the recipe with yogurt.  It makes it much creamier, and gives it different hints of flavor (depending on the yogurt).  I've actually dumped some fruit-flavored yogurt in there, and while it wasn't award-winning, it wasn't terrible.
-Combine with a slightly drained can of spaghetti-o's or other canned pasta.  Just make sure not to put too much of the juice in, otherwise it'll turn out very soggy.
-If you see a deal on some cheap noodles (bowtie and shell noodles work well), you can easily substitute those in the recipe.  It doesn't taste much different, but the textures are different, and if you combine this with any of the above methods, your taste buds will trick you into thinking it's actually quite different.  :D

Filoraene recommends:  "I usually make macaroni and cheese at home when I want a simple dish. I make it from macaroni, grated cheese, a small can of tomato puree (go for 6 cents here), half a choppen onion if I'm feeling adventurous, little pieces of bacon (about 70 cents a package). Add garlic, ground peppers or basil for taste.  The tomato makes it very healthy, the bacon makes it tasty."  I'll definitely try this one next time.  :)

Remember that these are all based on personal taste, so if it really sounds like you'd rather not try it, try something else new and differentHave fun!

(Edited 11-28-08 with some new suggestions!  Thanks guys!)