IPhone – a good GTD app with cloud sync on iPhone, iPad, and Mac

My solution was to use simpletext.ws, since the source is available I can use my own server to sync notes in my local network without having to worry about encryption. And on the iPhone I use the WriteRoom app to search and edit notes.

(As this is my first time using any stackexchange site I'm not sure if I should include this in the original question or answer it myself... apologies in case I'm not following the proper way of using the site.)

As of OS X Mountain Lion (coming in Summer 2012), Reminders will have an iCloud-syncing desktop equivalent.

Since Reminders is integrated with Notifications in iOS, and the desktop edition presumably will work with desktop notifications as well, this should be a good, out-of-the-box way to meet your (simple) stated needs.