If you feel a little more attached to it, so to speak, I've always thought the penis in the centre of the forehead look is very appealing. This also means that, and bear with me here, if you were to 69 with a woman, she gets oral sex as well as simultaneous anal penetration.

If your girlfriend does NOT enjoy anal, then you could always do the penis on the nose thing (think laterally here). (Just try not to sneeze.)

If she does not enjoy penetration at all, just chop it off (I'm sure we could find a needy recipient somewhere... *ahem*)