When it comes to task managers, there's no shortage of tools. But Checkmark, which arrived earlier this week on iOS, takes the limited location-based features of Apple's own Reminders tool and expands them into a full-featured app. Checkmark offers two notification tabs: one called "when" and one called "where." Time-based notifications are a simpler version of the ones in Astrid or any other to-do list, but the "where" reminders let you create location presets, complete with a location radius, then set reminders as you're arriving or leaving. The reminder text and chimes can either go off within a few minutes of meeting the criteria or be timed out up to an hour, and extra options in the iPhone or iPad's main settings let you customize how you're reminded and optimize the GPS tracking for higher accuracy or better battery life.
For dedicated list-makers, there are probably better apps. The tasks are bundled by location or time with no sub-lists, and there's no task syncing. It's also, sadly, iOS-only. Still, it's extremely simple to use, and tasks can be added with only a couple of taps. We've yet to come across anything that organizes location-based reminders better than this. Checkmark is $0.99 for a limited time in the App Store; it's compatible with iPhone, iPad, and iPod touch.