Red wine and chocolate is currently the "darling" of wine pairing. My roommate was having a red wine/chocolate craving, so we made chocolate souffle and paired it with a red wine. Though the chocolate we used in the souffle was "bittersweet" and had a 60% cacao content, the recipe called for sugar, so the actual souffle was much sweeter than the chocolate.
The amount of sugar in the chocolate is important because the key to a successful red wine/chocolate pairing is that the wine be sweeter than the chocolate. What red wine is sweeter than chocolate? Try a port or a dessert wine.
Just remember: The wine should be sweeter than the chocolate.
If you are eating a bittersweet or semisweet chocolate, try a Merlot. I paired the 2006 vintage of Sterling Vineyard's Merlot with bittersweet chocolate and it was divine! (It was also on sale at my neighborhood grocery store for $10.99).
My absolute favorite port is sold by the V. Sattui Winery in St. Helena, CA. It's "Madeira," solera-made, wood-aged brandy. The solera was actually recently discovered, and is over 120 years old. The after taste of caramel makes this wine especially great if pairing with a chocolate with caramel. You can visit the V. Sattui website at www.vsattui.com. They don't sell their wines to mass distributors, so you'd have to order straight from them (or better yet, go visit their tasting room!)
I ended up pairing the souffle with the Merlot, and it worked out great. Another popular red wine for chocolate pairings is Cabernet Sauvignon.
If you are intimidated by all of this, but you would like to pair a wine with your dessert, you can never go wrong with a sweet sparkling wine (sweet Champagnes are indicated by "demi-sec" or "extra dry"). Be adventurous and try new things--the only way to learn about wine is to drink it ;)