The most asked firearm question of all time...
What .22lr do I buy?
And the answer is almost always "you cannot go wrong with a Ruger 10/22."
The Ruger is rugged'ish, cheap'ish, accurate'ish, stylish'ish, enjoys a huge aftermarket support, can be made fully automatic, blah blah... basically an incredible all-around gun. You cannot go wrong, and DejaVu is right... it's un-American not to own one.
It's closest competitor is the Marlin model 60 (tube-feed) or 795(magazine-feed), which will do everything just as well, but without near the aftermarket support, and are also much cheaper.
But for those 2 guns, you have to be sure you want a semi-automatic. If it's a bolt-action you want, the best bang-for-your-buck is almost certainly the Savage MKII, with many models well under $200. It comes in many different flavors and is very affordable. The MKII-FV is a real looker. Throw any $50 scope on it and shoot quarter-sized groups at 100yds.
http://www.budsgunshop.com/catalog/product_info.php/cPath/975/products_id/24563
The step up from the Savage is the CZ 452/455, but you're gonna be around $400 for one.
Of course you can get a .22lr that looks like an AR/MP5/AK or just about any other type of full-sized assault rifle or sub-gun... but those always seemed to me as the cheapest way to just make noise. I have a buddy who loves his M&P .22, but I don't see the appeal.
I use my Savage MKII FV-SR as a teaching gun and to practice my trigger control and breathing. It's zero'd at 100yds and I rarely shoot it past 150 with some holdover depending on wind. It'll get a suppressor someday, which will give me an excuse to buy a Ruger MKIII... which is also a benchmark weapon.
If I was in the market for a semi-auto, I'd be looking hard for a used Ruger 10/22... you just can't go wrong.