While there are many, many different wine varieties that are cultivated worldwide, the main 'noble' varieties produce the best wines and the most sought after when choosing one for a meal. Here are the notable "Noble" grape varieties.

White Wine Noble Grape Varieties

Chardonnay - This noble white grape is known as a 'great white Burgundy', as it is an important grape from Burgundy, France. This was once referred to as Pinot Chardonnay as the grapes resemble Pinot Blanc.
Chenin Blanc - Can be both dry or sweet. While most Chenin Blanc wines are meant to be drunk within a few months of purchase, finer quality off-dry varieties may be aged successfully.
Gewürztraminer - Directly from the German - "gewürz" means spicy. This grape can produce a wide range of flavors, and off-dry to dry, but all have a nice, strong aroma. All Gewürztraminers are highly scented.
Riesling - Another highly scented grape variety. Originally from Germany, this wine grape can be dry, or sweet if affected with botrytis (see next picture below).
Riesling Grapes with Botrytis - Botrytis cinerea is the 'noble rot' that attacks grapes at harvest time. How it makes wine sweet is it increases the Brix levels, and can help smooth a wine grape.
Sauvignon Blanc - This grape is often combined with the Sémillon grape variety. This is also known as 'Blanc Fumé' or 'Fumé Blanc'. The one tasting note commonly related with this wine grape is "herbaceous."
Sémillon - Sémillon can be found dry or sweet (when affected by botrytis cinerea, see next photo).
Sémillon Grapes with Botrytis - Just as in the Riesling grape variety, the Sémillon grape turns sweet when affected with the noble rot, Botrytis cinerea.

Red Wine Noble Grape Varieties

Cabernet Franc - Not widely known, this is often combined with the Cabernet Sauvignon to smooth the tannins, since the Cabernet Franc has less tannins.
Cabernet Sauvignon - This noble red grape variety is a big red, with generally long aging times. As it ages is mellows out and loses the tannins it has so much of when young. Considered the King of red wines.
Gamay - The Gamay grape produces the Beaujolais which is a fruity red wine that can drunk slightly chilled, and most often enjoyed young.
Grenache (Noir) - This red grape variety is very dark in color, and is used for making good quality rosés. It is one of the grape varieties used for Châteauneuf-du-Pape AOC wine.
Merlot - The Merlot grape is dry, but having much less tannins than a Cabernet Sauvignon. The Merlot is another red grape blended with the Cab Sav to help soften it. Considered the Queen of red wines.
Mourvèdre - The Mourvèdre is another grape variety used in Châteauneuf-du-Pape AOC wine. When mixed with other varieties, the Mourvèdre gives the finished wine fruity notes of wild berries.
Pinot Noir - This very popular wine is also used in blending, such as when Pinot Noir and Chardonnay are mixed for Champagne. The Pinot Noir is an earthy red, and sometimes known as the Prince of the reds. While some of the best burgundies come from the Côte d'Or, the Pacific Northwest in the U.S. has some really fine Pinot Noirs as well.
Syrah - This very deep, rich grape thrives in hot regions, and is known as Shiraz or Hermitage in various growing areas of the world such as Australia, South Africa, France, and California. It has a reputation as being one of the most dense of all the reds, with a very high tannin content, therefore can be successfully aged for long periods of time.

For some unusual white wine varieties ideas for fish and seafood, read White Wine Varieties for Fish and Seafood from FishingChef.com.

Above picture credits:

This photo courtesy PDphoto.org:

White wine in glass.

These photos all through a creative commons license from Wikimedia Commons:

Sémillon grapes courtesy user Alison Parks-Whitfield
Gewürztraminer grapes courtesy user Marylou Jean
Syrah (Shiraz) grapes courtesy user Chrisada Sookdhis
Sauvignon Blanc grapes courtesy user VI
Riesling grapes courtesy user Tom Maack
Riesling grapes with botrytis courtesy user Tom Maack
Merlot grapes courtesy user David Carrero Fernandez-Baillo
Grenache grapes courtesy user Josh McFadden
Cabernet Sauvignon grapes courtesy user BerndtF
Chenin Blanc grapes courtesy user Chrisada
Mourvèdre grapes courtesy user Pancrat
Cabernet Franc grapes courtesy user Rosenzweig

Remaining photos were released as public domain through Wikimedia Commons:

Chardonnay grapes
Sémillon grapes with botrytis
Pinot Noir grapes
Gamay grapes