Alarms sits in your menubar, and clicking its bell icon there will drop down a timeline across the top of your screen, with the left side being "now." By dragging emails, files, notes, etc. to the bell icon, you can add new items and slide them around your timeline for the day, or drop them onto another day in the calendar on the right side. You can also double click to add an item manually.
When a scheduled item hits the "now" side of the timeline, the bell icon gently alerts you visually (and optionally audibly). You can handle the task and check it off, or slide it a little farther on down the line. If you click the view icon within a task, it will open the related item and leave a floating checkbox below the menubar. You can attend to the task and then check it off right there.
I don't know if it was the original intention of the developers, but for me this application is all about productive procrastination. Things that would normally distract me as I either handled them or added them to a list become really easy to just delay until I'm ready. There's even a snooze feature you can activate for configurable intervals. It's my favorite touch in the app, actually, as the gesture for activating it is rapidly moving your mouse back and forth a few times. It feels just like adamantly shaking your head "no!" It also syncs with iCal, so you can put items on your timeline at work and have them pop up reminders back at home, and Growl for more relatively unobtrusive notifications.
The application is functionally simple, but very polished. It's labeled as a "preview" right now, but I haven't seen any inkling of instability or rough edges. The "early bird" discount puts the price at $12US. You can try it for free, though, and see if you dig it as much as I do.