urine is high in nitrogen, and nitrogen can be very beneficial to plants. However you can also provide too much N, which can burn them - especially if they are already getting nitrogen as part of other feedings.
I pee on the compost bin all the time. It gets tended in and builds the nature of the compost.
As for the ick factor above, meh. A little pee is no worse than huge chunks of cow manure in terms of ick factor, but the plants love it.