The asset API has for goal to provide some kind of abstraction layer for the file management.
It is not yet ready for production use
(but I'm working hard on it and try to do may best)
It is composed of a main module and some sub-modules (implementing handling of some file types like images, pdf, flv video, swf files, openoffice documents and archives).
The main module provides (limited) block and filter features and an asset browser too.
There's also some views integration and some other useful things (like an asset importer and a module managing the conversion of video files into flv - using FFMPEG but extensible).
Every asset is in fact a node (which allows some nice CCK extensibility).
This version of the module is for Drupal 5.x but an other version for Drupal 6 is already started.
By the way, some files of the project are missing because I'm not sure to be allowed to redistribute them under GPL license (if somebody could help me to figure out what I'm allowed to redistribute, I'll be really happy).
I already knows that the project is missing documentation and some integration with TinyMCE or other WYSIWYG editors (for example, because one of the goal is to provide some really user friendly tools too and replace IMCE).
The development of this project was started just after the DrupalCon 2007 in Barcelona.