The online racing simulator
On the international scene, I really like watching the MotoGP-series (although I don't own a bike, and never will) - there's awesome racing going on. The Aussie V8-supercars offers some serious racing as well.

The Danish Touring Car Championship is pretty damned good (and often far more entertaining than the WTCC counterpart) and for some arcane reason, this F1 season has been quite enjoyable.

I do prefer "limited" racing where there's some effort to keep everyone on very level terms. And there's a lot of good to say about the low-budget classes that provide the "appetizer" for the danish touringcar events. Seeing a huge grid of dated hot-hatches giving it everything it's got, still gets me all warm and fuzzy inside.

Old-timer racing and hillclimbs and stuff, with a chance to see - and hear - some of the old greats, deserves honorable mention as well. I'll never forget the day I heard an old Ferrari 250GTO being fired up. *shudders*
anything with 2 wheels makes great racing

I loved this years manx TT. them guys doing 200ish down a street road with slipstreaming madness :P
F1 this year is also fun but only to see a rookie 22yr old come and show these so called best drivers in the world that its easy
TBH the best racing is going to your local track and watch anything thats on

FGED GREDG RDFGDR GSFDG