Mac: There are many great apps for taking various kinds of notes, but it's frustrating to have to use more than one because some services just don't fulfil every need. Notesdeck attempts to solve that problem by combining four popular services -- Evernote, Simplenote, Dropbox and iCloud -- into one app.
Notesdeck is a very simple app. It puts the four services it supports in a left-hand bar, and you just need to click on each to log in. Once finished, you'll have access to all your notes from that same sidebar. Make changes in any services and Notesdeck will update. It's pretty straightforward. The app also includes a full-screen editing mode for distraction-free writing and several interface adjustments.
While the app is very functional, the interface wastes a lot of space with excessively blocky text and shows every service even if you don't use them. Sticking service setup in the preferences and only showing active services would help, but smaller text would also be nice so more of your folders can fit on the sidebar (which is important if you use Evernote and/or Dropbox). While not a new approach to interface design, iTunes handles its sectioning well. Big text may look cool, but it makes the app a little hard to use. This is also the case with the notes list, which could save a lot of space by scaling things down a bit. Aside from the interface issues and the relatively high price of $11.49 (for a class of app that's often free), Notesdeck is exceptionally useful if you have notes in various services. For those with this specific problem, Notesdeck is very much worth a look.
Notesdeck [Mac App Store]