I found this great site for looking up maker's marks on glassware. It not only has the old marks like Westmoreland, Imperial Glass and others that are recognizable. It has marks of makers I have never heard of before, or didn't realize marked their glassware.
I am a real stickler on knowing what maker and what pattern a piece of glassware is before I will list it on ebay. Those keywords are what brings the buyers to your items that they are looking for. The more relevant keywords you can get into your title, the faster your items will be found.
Check out this site!! When you join, you get 10 free "lookups".