UpdateServer

[Bakual]

As soon as you make the plugin available to a bigger base, you should consider adding an updateserver. Otherwise people will not catch new versions of the plugin.

[dongilbert]

Good point. I typically write custom extensions for long term clients, and maintain them, with no need to setup an update server. Can you point me in the right direction?

[Bakual]

You need to add this part to your manifest:

<updateservers>
    <server type="extension" priority="1" name="YourDomain.com">http://www.yourdomain.com/path-to-whatever/filename.xml</server>
</updateservers>

Make sure there is no space around the URL itself or it breaks. At least that was the case in earlier Joomla versions, maybe it's fixed now 😃

Doc is here: http://docs.joomla.org/Deploying_an_Update_Server

Instead of manually creating this XML file (which is just tedious), I use ARS (https://www.akeebabackup.com/products/akeeba-release-system.html) from Nicholas which makes this quite easy.
However I don't use the URL created by ARS as the updateserver directly. I use an imaginary URL (www.mydomain.com/updates/plg_my-plugin.xml) and use mod_rewrite to redirect it to ARS. This way I could change ARS to another solution if needed without breaking the updateserver for my users 😄