I go with batch numbers in the format year number-batch number. For example, I made an American Amber last week that what the 14th batch of this year so it got numbered 11-14.
I used to put an initial on it but that got a little confusing. My girlfriend wanted to give some wit to someone and assumed BW stood for Belgian Wit. They were very surprised to get an American Barley Wine instead of a wit.
Batch number on caps and now that I'm kegging I just got nice badge holders that I put index cards in with the number, name, and date. All of my batches are numbered with full details in iBrewmaster on my iPhone for quick reference.
Hmmm...I wonder if I could work out a system to print out a label with batch number and a bar code. I'm imagining scanning the bar code with a smart phone to get all the details on the brew. My geekiness knows no limits!