A simple seven segment display.
I haven't made a PCB for it yet, nor have I tested if it is usable on veroboard. The segments can be used with 3mm standard LED's, or with SMD LED's.
Update: Sorry, it's not (yet) veroboard compatible. I might have to design another one :-)
Instead of the diffuser, you can use a piece of paper as well. SMD LED's are recommended to get the maximum distance between LED and the piece of paper.