I don't do cash gifts... graduations, weddings, birthdays... I prefer shopping for something the person (or couple) can use instead.
Dh is the eldest grandchild on his dad's side ...there are about ten of them and the next eldest one is 18yrs younger...so we've been going through a LOT of graduation parties over the last few years!
Some gifts we've given:
One of those plastic shelf units on wheels filled w/ supplies and office stuff (stapler/remover, pens, pencils, sharpener, ruler, scissors, paper, paper clips, glue, tape, etc.). Sounds kind of lame but all that stuff really adds up and both of the recipients (we made sure they were going away to school and staying in a dorm) came to us the following Christmas telling us how much they appreciated the gift... and how all their friends at school appreciated it too!
That was before I had kids and had the time (and energy) to put it together.
Last year we gave dh's three graduating cousins portable USB drives (aka memory sticks). They all had their own laptops but we thought the USB drives would be helpful transferring files, etc. Again... they came back at Christmas thanking us for how useful they were.
The last cousin graduated last week... he received a wireless mouse. I can get back to you in December to tell you how useful it was for him!
Oh and the wedding we went to over Memorial Day... they received a Bed & Breakfast gift certificate from Costco. They LOVE it and can't wait to use it!