I just regenerated my stats so I'll share...
Escape Pod has been out for just under 10 weeks at $1.99. In that time it's sold 4563 copies.
Alphonetic has been out for 8 weeks at $0.99 and has sold 573 copies.
Sleeps to Christmas has been out for just over 3 weeks, has been downloaded 101,236 times, is free but has generated $2300 in advertising revenue.
So what can we take from this?
Escape Pod I'd consider succesful. It's paid back the time I spent on it at a decent rate. It's caught some breaks like being well reviewed and was featured in BBC Focus Technology magazine.
Alphonetic was NOT worth the implementation time. I guess it's a bit of a niche app.
Sleeps to Christmas is an interesting one. It has one advert along the bottom of the screen and despite a really poor fill rate (only 60% of users actually see an ad, since my ad provider is struggling) it's generated an exceptional return. It took me 4 hours to implement the first version, with maybe another 6 hours on updates. So that's a good return...