"Node Recommendation" Module alternatives
There are two excellent modules, both compatible with Drupal versions 6 and 7:


If you want to display similar nodes calculated by the actual node content, try Similar entries
If you want to display similar nodes calculated by some sort of taxonomy setup, try Similar By Terms


There's also Relevant Content, a module which allows you to configure the recommended nodes based on many different things, with different block configurations and stuff for dealing with CCK. I haven't used it, but I've heard it's quite good.