Views Fusion allows one to fuse multiple views into one. So you can build fused views that display information that is stored in multiple nodes - useful for tabular views. It uses node relations for joining the appropriate nodes together.
Currently the views_fusion module needs the nodefamily module for getting the node relation information. However in future other node relation modules could also provide their data for views fusion as it is written generic.
There is also a patch for the CCK node reference field, which adds support for views_fusion.
Warning: Using this module is complicated and I can't guide everyone - so it's only recommended for experienced users. Furthermore there might be troubles with some special views filters/fields,... Be sure to study the README carefully.
6.x: There won't be a 6.x compatible version as views 2 (for 6.x) can handle relationships already on its own! Great!
- Views (at least version 1.6 or the latest development snaphot)
- Node Family (or another supported node relation module)
Status: There won't be any active development in the drupal 5 version or earlier any more.