Under active development

Provides a "boolean" field type with an additional state of "not set" in addition to the usual "true/false" or "on/off." A separate display string can be defined for each state.

Code per Node makes it possible to add custom CSS and Javascript per node, per content type, per block, and globally. The code is stored in the database, but served from the file system. It also supports syntax highlighting with CodeMirror.

CPN was covered by a recent webinar by Mediacurrent: http://www.mediacurrent.com/blog/webinar-code-node (this is also mentioned in DrupalEasy podcast 120)

Provides a database table containing indexes to entities of any type. This module doesn't do anything on its own and should only be installed if another module depends on it.