Billings, my personal favorite time-tracking, estimating and invoicing application has just updated to version 3.5. The developers, Marketcircle, are labeling it the "Trojan" release due to its mostly-under-the-hood improvements. Under the hood, but not insignificant. The major changes are related to a database engine overhaul (subtly continuing the car metaphor for your reading pleasure) and improvements to the way Billings interfaces with Address Book. Rest assured that "Trojan" refers only to the nature of the updates, not to any kind of malicious software).
I'm certain that those covert improvements, while exciting for current users, probably won't be enough to stir the passions of others. The fact that Billings 3.5 is now able to sync over WiFi with your iPhone might be cause for celebration... if only we had a version of Billings on those clever devices. Fear not, Billings Touch has been submitted to the App Store and is nearing availability as you read this. As a beta tester, I can't talk about the features of Billings Touch, but I think it's all right to tell you that it's everything I'd hoped it would be when AJ first mentioned it.
Billings is $39.99US, and Billings 3.5 (free upgrade for 3.0 users) will be required to sync with Billings Touch. Check out a free trial at billingsapp.com.