A beer marinade provides a nice twist to the ingredients. Beer definitely adds a different level of flavor to a marinade. it has even been discussed as possibly reducing the formation of carcinogens. How 'bout that? An added bonus.
One of the reasons I like using beer is because I like the taste. The other reason is that I have been brewing my own beer for several years. And I have found out that homebrew tastes much better than commercial beers.
One of the best smells (IMHO) in all of creation is fresh hops. I had heard the term before, and knew it was something used to make beer. But I didn't know, until I started reading more about brewing, that hops are flowers.
They act as a preservative, as well as imparting bitterness (to offset the sweetness of the malted grains). Well, there's a topic for a whole 'nother website.
Varying the amounts and proportions of grain, hops and yeast can create hundreds of flavor possibilities. It's just like food, I suppose. Fresh ingredients in a recipe will always taste better.
Whether you brew your own beer or buy it, this is really a good time to experiment. A lot of people like to use dark beer in a marinade. This is definitely a matter of choice.
You know what beer you like. Start with that.
Here is an example recipe for you to consider. Naturally, feel free to adjust it as you see fit. Enjoy yourself... and have another drink.
1 1/2 c. beer (one 12oz can)
1/2 c. olive oil
3 clove minced garlic
2 tbsp. lemon juice
2 tbsp. sugar
1 tsp. salt
1 tsp black pepper
Dash of Tabasco
1 tsp fresh grated ginger
Combine the beer with the olive oil. While stirring gently, add the rest of the ingredients. Marinate beef and turn occasionally. It's now ready for the grill when you are.