There is a large number of plugins for Live Writer, and all you have to do is pick the one that suits your current needs. Even if you need a plugin for another program from the Live suite, the common denominator is always the Windows Live Gallery, which is at 👻 Microsoft shut down Windows Live Gallery long ago..
Plugins specifically for Writer are at 👻 Microsoft shut down Windows Live Gallery long ago.. I will not list the others here, because they are not used that often. So on the page mentioned you can download plugins for these programs: Windows Vista, Messenger, Live.com, Spaces, Events, Windows Search and SideShow.
You can also subscribe to an RSS feed, so you will never miss anything interesting. On the same page you can also submit your own plugin through a form. Creating a simpler one is not hard at all, so you may eventually find a tutorial on my blog. It depends on how much time I have. But if you would like to set off on this path without me, I will point you to 👻 Microsoft shut down Windows Live Gallery long ago..
Unfortunately, as of today no applications are displayed, even though they are there. See, for example: 👻 Microsoft shut down Windows Live Gallery long ago..
I do not understand why Microsoft does not finish this page properly. After all, it has looked like this practically since Live launched, and that is quite a few months now. What annoys me most, though, is that I cannot see which plugins are currently there, so I cannot give you any overview here.
EDIT June 23, 2012:
Plugins for programs from the Windows Live Essentials suite are now at a new address 👻 Microsoft discontinued Windows Live Essentials plugins long ago..