KSP-AVC Add-on Version Checker
On starting KSP this plugin will search your game directory for '.version' files. It will then proceed to check each one for version related issues. If any issues are found, an issue monitor will be displayed notifying you of what they are. There are two main types of version issues, with the first being related to the add-on's version and the second being its compatibility with your version of KSP. Some add-ons will also support a download option in their version check. If you require an update of an add-on and it has a download location set, you will be given a button which will open up your default browser and take you there. This could link directly to the .zip file or to a page with details on how to update. Note that you will need to close down KSP, install the updates and then restart KSP for them to work.
Copy the complete folder and contents of KSP-AVC into the GameData directory within your Kerbal Space Program installation.
For simple management of your version files for developers your can use the KSP-AVC Online website at: ksp-avc.cybutek.net.
Completely voluntary, absolutely amazing, and really does help me out a lot!