KOffice Calligra Suite

The KOffice project was replaced by Calligra Suite, after some disputes. Calligra Suite is a fork of the 2010 codebase.

IBM Lotus Symphony

uses code from OpenOffice.org and includes enhancements such as new sidebars in its user interface.

Not in the repositories, but I think it is worth mentioning, you may give it a try and see what it brings new to OpenOffice.org besides the interface

Read more: http://www-03.ibm.com/software/lotus/symphony/home.nsf/home

Other Useful Options

For calculations one could use gnumeric, octave and Python with numpy. A fairly good lightweight word processor, Abiword is available.

For document creation, Latex and Context are excellent systems, the learning curve is a little steep when it comes to Tex based document creation systems, but when one starts reaping the rewards of the power of these systems one will see it is a small price to pay.

For people just starting with Latex, an Interface like lyx may be used. There is no substitute for a good Latex editor though, texmaker is a fine one.

Scribus may also be considered, while it is a page layout program and not a word processor there is a story editor that have similar behaviour to a word processor and there are many instance where something like this is better for document creation than a word processor.

For drawing Xfig and Inkscape are quite good.

For database, sqliteman interface to the sqlite database system