Related-Posts-Plugin for index page (Sidebar) needed

Hello there,

I’m searching for a Related-Posts-Plugin. I know, there are tons of them but the one I’m searching for, should be able to display the related items in the sidebar of the start page (index), not only the single page. The top most post of the start page should be relevant for this.

One plugin I’ve found was ?Similtary? but it works not properly. It follows not the first post but the last post of the index page.

Any ideas? Thanks!

C.H.