If you can stomach a hit to your effective Bard level, the customary single dip in Mindbender gives it as a class skill. Mindbender requires 4 ranks in intimidate to start with, so you can enter by 9th level, which also means you can pick it up right there and then. So it's like Virtuoso in a way, where the former gives up a level of bardic music and the latter a level of spellcasting.