I am puzzled. This was a very valuable option in D6 CCK, but since it moved into core, I can't find the option to create a noderef field (found a term reference field, though). I know it must be out there, where is it?
The project that maintains the Drupal 7 versions of the "node reference" and "user reference" field types is References.
Part of the code of CCK has been ported in core code, but some code is still living in third-party modules. CCK itself has a version for Drupal 7, which contains the code to update from Drupal 6 to Drupal 7 (among other things).
I found this summary very helpful.
I would skip References, it looks like it is on its way to being deprecated.
For simple D6 style user and node references use Entity Reference. This module is required by Drupal Commerce so as long as that project is alive and thriving so will entityreference.
If you looked at entity reference and your needs are more complicated check out Relation. You can come up with a very complicated entity relationship scheme using relation, but I wouldn't go down this road unless you know you need the flexibility.