Mac: Back in the days before Mac OS X, Apple created a notes app called Stickies to let you post little coloured notes all over your screen. Despite a lack of updates for years, it's still widely used and a favourite among many. Nootes is an app that works similarly to Stickies but provides a number of additional features. If you've wished for a Stickies upgrade, you'll want to check this out.
When it comes to simple, syncing note apps, we still love Notational Velocity, but I'm probably not the only one out there that uses more than one notes app to manage text. While I was never a big Stickies user, I always liked the idea and essentially repurposed it with TextEdit by leaving information I planned to use at some point but just needed to store there temporarily. It didn't really make a whole lot of sense, so I really came to like the idea of Nootes because it's kind of a combination of both. It works great as a series of little scratch pads. You can choose between several styles, just like Stickies, but you can also write full screen so it doubles as a distraction-free typing app. On top of that, you can password-protect your notes if you'd prefer to keep them private. Versioning is also built in, so you can go back to older versions of your notes should you want to recall something you deleted.
Overall, it's a nice little upgrade for the Stickies app that hasn't seen an upgrade in years. If you can pry yourself from a program that's been with you (possibly) longer than Mac OS X, give Nootes a try.
Nootes ($0.99) [Mac App Store]