Source: My girlfriend does promo modelling from time to time.

Here are a few things that I found interesting:

* Bikini modelling (perhaps obviously) pays the most. Numbers are in the $50-75/hour range.

* For non-bikini modelling, liquor gigs pay the most. About $35/hour. Non-liquor gigs are roughly $20-25/hour.

* A lot of girls do this full-time.