Here's what NOT to bring to Thanksgiving dinner:
Cabernet Sauvignon (for the love of God, don't bring Cab)
Merlot
Petite Sirah
Chardonnay (unless there is a crab dish)
The varietals above are simply too much for Turkey Day.

DO bring:
Beaujolais Nouveau - It's in season. But be warned...Stay away from this wine if you're particularly offended by floral, aromatic varietals.

Pinot Noir - Spend $20 or more and you should come out with something pretty decent. Stick to Northern California and Willamette Valley Pinots (pre 2005, if possible).

Champagne or Sparkling Wine - Again, spend at least $20 or opt for the pink-wrapped Sophia Coppola (a bargain and a fun conversation-starter). When in doubt, bubbly is always appropriate.
The varietals above will pair nicely with almost all Turkey Day fare.

Cheers!