I used to love FileHippo.com for keeping a lot of my well-loved tools on Windows up to date with its tool that you could check to scan your current program versions (both freeware and paid - in the case of paid it still works to download the latest installer as your license is still located in the system - I assume it would work for Mac too), and a simple repository on the site to directly download the new updater installer files from once the results screen online shows you what you can download and update.
Common apps monitored by FileHippo would be VLC, uTorrent, Firefox, Chrome (all the way up to dev channel), CCleaner, Adobe Reader, Adobe Air, DivX, Safari, Skype, Thunderbird - and all these apps I now have on the Mac too.
Is there anything like this for the OS X world?
MacUpdate.com looks great, but it doesn't seem to officially offer an equivalent 'update checker' app from looking at its website.
And as for Apple's Mac App Store solution, that doesn't cover the apps I listed above so could not be considered an adequate solution, unless all those players unanimously participated in that ecosystem which I don't think is the case.