MACFOTO  that's totally 1998! not only the gui…i mean the "100 clicks" and more! good for managers & programmers but not for freelancers! sorry, free is not enough!   
(Version 2.2.1)

ESPIRIDION  Two years have passed since my previous TR review.

During this time I tried Things and got a license for The Hit List. Both are very good task managers, although a bit over-priced IMO.

My choice for a GTD tool is still Thinking Rock.

Great support, truly a GTD-centered application, and continuously improving.  
(Version 2.2.1)

HUGH JARSE  I've been using this app for 6+ months now and I have to say it's really good, it sticks to the GTD methodology and is properly cross platform. Because I need access to my tasks everywhere, by using dropbox I can keep my tasks synchronised between my work (windows) laptop and my mac's without any issues at all.

The developers have brought the application on well since I started using it and they encourage user feedback and actually listen to it!

It's not the prettiest app out there (blame the Java tool set not the developers) but if you're more worried about getting value from a tool than how pretty it is, this is the tool for you. It does exactly what it says and does it well. As for value for money, I think that speaks for itself.

Great Job Guys!!  
(Version 2.0.1)

SIGIL  This app seems great. The price is perfect lol. I only have one gripe. This app looks like a windows app. Aesthetically speaking this is not what I would expect a Mac app to look like. This reminds me of Calorie King...Great app, but yuck! That said, it is free and the other Mac alternatives are either not true GTD applications or very expensive.   
(Version 2.0.1)

ALJUK  This is, hands down,the best GTD app on any platform.

If it's Dave Allen's system that you use, then this app is perfect, and your only serious option.

There are a few small java clunks, and it can occasionally seem a little slow, but in the scheme of things, that's irrelevant.

If only I'd discovered this sooner...

I use FileSync to keep the data files sync'd between my desktop and laptop, so I always have up-to-date GTD data wherever I am.

Wonderful.  
(Version 2.0.1)

SAMPLER  See the Developer's web site for pre-release issues of Version 2.0  
(Version 1.2.3)

ESPIRIDION  Since I’m surprised at the recent reviews I have read for other GTD applications, I thought it would be useful to add a review for Thinking Rock.

Out of all the applications I have tried, Thinking Rock is one of the few that follows David Allen’s GTD methodology in detail.

The developer is very responsive, bugs have been fixed and requests have been incorporated into the application. Right now Thinking Rock is quite impressive for a version 1 software, especially given that it is available for free. I would encourage people who find the application useful to donate and show their support.

For comparison, here are some of the applications I have tried:

1. Kinkless GTD. Great and free, but requires OmniOutliner Pro. For me Thinking Rock has been easier to use on a daily basis. Perhaps OmniFocus will eventually be a great GTD program, but for now I prefer Thinking Rock.

2. Midnight Inbox. Looks beautiful, but it lacked a lot of functionality for my use.

3. iGTD. It’s very rapidly evolving, but at the moment still lacks some GTD features (e.g., Waiting For, Delegated, Reports, etc.)

4. Actiontastic. Again, looks interesting but lacks functionality (e.g, Delegated, Waiting For, viewing multiple projects at once, etc.)

These 4 programs come to mind since they are recent, but I have used others and always return to Thinking Rock. My advice is to download them, use them, and compare them. Each person has different tastes and preferences. My choice is Thinking Rock since it allows me to follow the GTD methodology, enables me to print a variety of reports (e.g., by context, by person, by project, etc.), allows me not only to view but also to sort multiple items using different criteria (e.g., action, project, context, etc.), has a very useful pop-up help, works on Windows and Mac (this was particularly important since I had to move back and forth between a PC and my Mac for some projects), has a very detailed Help file, and is very easy to use. After a couple of times of using it I was getting things done with the help of the application, and I TRUSTED the application. This is essential for GTD, and I can’t say the same thing about alternative programs.  
(Version 1.2.3)

GREGSGRAPHICS  I agree with Kaleo... a better UI and integration with the OS would make this app perfect.  
(Version 1.2.3)

KALEO  A very nice implementation of GTD! I have tried just about everything I could find for the Mac. My top 3 are kGTD (Requires OmniOutliner Pro), Process, and Thinking Rock. Only TR is free; Process and OO are commercial.

Nice Features:

TR allows nested folders for projects and sub-projects.

Next Actions can be listed and sorted by date.

Much more!

Feature Requests:

A nicer interface.

Make Overview page a set of links.

Add a few more time-based viewing options (yes, I know not strictly GTD).  
(Version 1.2.1)

MARTHI  Great support! Very kind!  
(Version 1.2.1)