Sometimes you just want some really big LEDs! It's no problem to go out and buy some that are slightly larger than your standard 5mm LED, but if it's something larger that you desire for a project then the quick and easy solution is, as always, hot glue. It's a fairly straightforward and inexpensive process, with the possible exception of finding an appropriately-shaped ice cube tray for the casting process. The LEDs look quite cool when lit up and add personality to any projects that have exposed lighting.
I made this project over at TechShop (http://techshop.ws/