Anxiety is a lightweight task manager. Unlike other big-name task management apps for the Mac, such as Omnifocus and Things, Anxiety is all about the small and unobtrusive. While those other task management apps get bloated with projects and recurring tasks and giant windows, Anxiety minimizes its workings to a simple, small window, with merely a function to add a task, associated to a specified calendar. I admit, those other features (projects, recurrings, etc) may be useful to some people, but I have personally found them to be unnecessary.
Anxiety integrates seamlessly into the Mac OS X environment. It has the look and feel of an Inspector from another application. Anxiety has the option to hide its Dock icon and live solely in the menubar, making its imprint on the system (at least graphically) ever smaller.
The tasks themselves are handled in the user's choice of iCal or Mail. That is, when one adds a task to Anxiety, an identical task is automatically added to either iCal or Mail. This allows Anxiety to use iCal's notifications, or to send the user an email concerning a task. (While this is nice, I do miss the stamp notifications of Things.) I do not have MobileMe, but I would imagine that, by having MobileMe, one would be able to sync one's tasks from iCal to one's iDevice or laptop. (Hopefully, the rumors will prove true and Apple will make MobileMe free soon.)
Anxiety is a tasty little task manager which is great for users who need to enter in a task quickly and without hassle. Although it is missing some functions of the larger task management apps, it holds its own, simply and without impression.
Anxiety is a free download from Model Concept. (Donations are appreciated.)