Hurray! My wife gave me the GO AHEAD to order my first piece of "L" glass! What kinf of filter should I put on a Canon 70-200mm F2.8 L IS USM. I've heard some folks do put anykind of filter at all on this type of lens. The lens should be here tomorrow and I wanted to know if I should have a filter ready for it or should I just leave it be?

There's two distinct camps on this one, personally I fall into the no filter camp and rely on the lens hoods as protection. I do have a Hoya super hmc 77mm that I can use if I'm in a particularly dusty or wet environment, but for normal day to day use all my lenses are kept unfiltered.
YMMV!

I see that you are a newbie on this forum. Normally a gear question is sent to the "General Gear Talk" -forum. As for your question. As I see it you have two choices. Donīt put a filter at all, or put a very high quality UV-filter (B&W MRC or Hoya Digital Pro are both good choices) for protection purposes. If you put a cheap filter on it it will degrade to a noticeable degree the picturing ability of that great lens.

What Ronan wrote.

I use to use filters and now, other than a CirPl have abandoned, unless necessary, protective filters.

Use your sunshade religiously for sun as it will absorb most front end impacts. Be careful with your, of course and use the best filters possible if you much use a filter. HOYA S-HMC great! B+W MRC filters better.

Always use a filter when necessary in the case of nosey wet dog noses, curious George sticky children's fingers, blowing snow, rain, salt or sandy spray.

Hope the above helps.