Create a Quote Number

We used CustomObj01 as a Quoting function.  We want to assign a Quote Number and used [<CustomObject1Id>] as the default Quote Number.  This works well giving us a unique number each time but the Quote number has no intelligence and is hard to remember.  I can add the 1st three Chars of the Account Name plus the date ('ABC120514') but want to append a sequential number to the end so we don't get duplicate numbers.  Looking for something like 'ABC120514_001'.
Is there a way to add/track a sequential number to the basic quote number?