Actually you can, there is service called vanity pool where people pay for vanity addresses and anybody can find the address and get paid. It uses the split key method and thus is completly safe to use such vanity address. You can download and run oclvanitygen and start finding vanity addresses others request and get paid if you find the address.

Just for comparsion, your computer CPU can search through about million Bitcoin addresses per second, GPUs few millions Bitcoin addresses per second. But to find longer vanity address (6 and more characters), you need to check a lot of random Bitcoin addresses to find match to your defined starting vanity address, and it might take a lot of time (days, months)