I clicked on a Facebook ad, for the first time the other day. It was to promote ASIC's Track My Spend app. Jess has praised the Smart Budget app, but at the time, it wasn't available on Android or iPod touch, so I couldn't use it. Thankfully, Track My Spend is Android-friendly and I've really enjoyed using it.
It's really simple to use, has a relatively uncluttered and clean layout. It's been a really helpful way to track my money, as well as keep me more aware of where my money's going. This one's got my thumbs up!