Billi uses Heartgard Plus for small dogs and Iverhart. The reason for 2 is because some months she will take her Heartgard, and others she won't. When she doesn't, I give her the Iverhart which is a total PITA and an event in itself- gotta crush it, mix with food and feed it by hand over the course of the day. She's a princess.
I use Frontline + for under 10lbs. I use 1 drop every 2 weeks since I bathe her so frequently. I am interested in learning more about Revolution though, since I've heard so many good things about it here.