Mac OS X: The Mac App Store is great for providing all your app updates in one place, but if you'd prefer not to use it, free app AppFresh will keep all your downloaded apps updated from one single window.
AppFresh searches your computer for installed applications, widgets, preference panes, plugins and other updatable goodies and organises them by available updates. It gets its update info from Apple Software Update, Sparkle, Microsoft AutoUpdate, AdobeUpdater, osx.iusethis.com, and more. No longer will you have to update apps right when you need to use them; just launch AppFresh every once in a while and let it update everything.
We've mentioned AppFresh once before, but thought it was worth re-visiting after the launch of the Mac App Store. One of the App Store's biggest draws is its unified update system, but in addition to the many downsides of the App Store, it won't update apps you downloaded from the web. AppFresh will do that and then some. It'll even check for system updates, so you won't even have to run Apple Software Update anymore. If you aren't already using it religiously, hit the link below to check it out.
AppFresh is a free download for Mac OS X. Note that it's still considered a "development preview", and while it works great for many people, you may prefer something more stable. In that case, we recommend checking out the App Update widget.