I've been using Macdive for some time now to keep a logbook of my dives on my Mac.
I'm very pleased with the features this app has to offer. Dives can be downloaded directly from my divecomputer, merged with information out of Divelog for iPhone and stored on my Mac.
The software seemlesly integrates with Divelog, which i use on my iPhone. Although not all information is synced between the two, the developer added most things to the sync in the last update.
A simple feauture request by email during development of the latest version caused the request to be immidiately put in this latest version.

When i had problems using the app, the developer immediately replied to my request for help and went all the way to solve my problem, which he did. So i can't say anything else than that the support for this app is excellent!

I can reccomend this software to everyone who is looking for a program to keep a logbook of their dives on their computer. It is deffinately worth the little amount you have to pay for a license.