Car configurators are one of the all-time great online time-wasters. If you want to dream bigger, though, Boeing will let you (virtually) paint a new 787 Dreamliner.
The "Design Your Own" program is paint-only and not really a true configurator; fitting the cabin for a commercial airplane requires something akin to a professional interior designer, and it's not like you're going to be deciding between piano black and carbon fiber for cockpit trim. Playing with livery is enough to keep you preoccupied for a good while, though, and if you've thought that some corporate designs err on the side of drab here's your chance to set things right.
The aircraft-positioning and brush controls are a bit clunky and hard to align; it's clear that Apple didn't do the interface. That said, once you get the hang of it (hint: the cursor point is the tip of the brush) things flow quickly, and some of the options like various heraldry patterns are quite clever.
The website gives you the opportunity to save your work for public display and check out other creations. Should you wish to transfer your pattern to a real aircraft, however, we advise speaking with the senior loan officer at your local bank: a 787 starts around $200 million before that interior designer gets to work. We hope the paint is part of the deal.