Sure, several people have written custom smart apps that do this. Most assume that you have a button device like a minimote, but you could also do it with a virtual device that just shows up on your phone.
Check the quick browse links in the communitycreated wiki in the smart apps section for “lighting.” There are several in there.
If you haven’t used custom code before, here’s the FAQ for that. It’s pretty straightforward, basically you copy someone else’s code and paste it into your account.
And this is what a minimote looks like. Very popular in the community. If you shop around, you should be able to find one for around $20. Each button can be a short or long press, so that give you eight options.
