I've been using Foldera with my GTD implementation for a couple months now. I really liked the idea of using an online and paperless system because I'm a designer and web developer so I'm in front of the computer anyway. Plus I can be anywhere and have all my tasks and projects at hand.
Foldera has worked pretty well for me. There were speed issues at first but that's getting better (if you are using a Mac I'd suggest using Camino as your web browser).
Here's basically what I do:
1.) keep note cards at all times for quick "capture" and hold them in my physical in box.
2.) I create a project folder for whatever project my tasks are for (I'm finding I really don't need very exact folders with Foldera's filters.. So, if I get an idea for advertising one of my websites I simply put it into the 'advertising' folder instead of 'web advertising - www.mysite.com')
3.) add a task to whatever folder I want it into. When I make a task I always put "@ bla bla: 'task here'". For example if I need to get milk I'd type in "@ errands: get milk" Make sure you leave a space after the @ and then add the context to the task.. for some reason Foldera filters it funny if you don't add the space.
4.) Go to "view everything" and filter for the contexts you want. It's that simple.
There are a couple problems with this though. First I'm having trouble with Foldera not showing me all of my filtered tasks. For example, when I add a filter called: "@ home" I may only get 10 or 15 of the actions with this context.. even if I have 100. I've written Foldera customer support about this but never got a reply. The only work around I have found is to show completed tasks as well as uncompleted tasks (under task preferences), and don't filter.. just scroll down to the context you are looking for.
Second, there is really no way (that I have found) to sort my project folders. It is a real pain to scroll through 60 folders that aren't sorted in any way.
I also have trouble with deleting old project folders. Half the time I delete them only to find they are still in the project folders again!
Also, I am finding Foldera still locks up on me at times. It's getting better (or I'm getting more patient), but still a pain sometimes.
Finally, I wish there was a way to archive the completed project folders rather than deleting them. I'm so used to the way Gmail archives everything I find it hard to "let go" of finished folders etc.