For those that still have nice grilling weather, and for those that can wait till next summer 
Weber's Tangy Barbecue Sauce
1/2 cup chopped celery
3 TB. chopped onion
2 TB. butter
1 cup catsup
1/4 cup lemon juice
2 TB. sugar
2 TB. vinegar
1 TB. Worcestershire sauce
1 tsp. dry mustard
Dash pepper
In a medium saucepan, cook celery and onion in butter until tender. Add remaining ingredients and bring to a boil. Reduce heat, cover, and simmer
15 minutes. Serve warm.
Source: Weber's Art of the Grill
Weber's Tangy Barbecue Sauce
1/2 cup chopped celery
3 TB. chopped onion
2 TB. butter
1 cup catsup
1/4 cup lemon juice
2 TB. sugar
2 TB. vinegar
1 TB. Worcestershire sauce
1 tsp. dry mustard
Dash pepper
In a medium saucepan, cook celery and onion in butter until tender. Add remaining ingredients and bring to a boil. Reduce heat, cover, and simmer
15 minutes. Serve warm.
Source: Weber's Art of the Grill