Gnumeric / Guppi
the fully featurefull spreadsheet

Features not yet implemented:
Pivot tables
Bonobo by default - Gnome 1.4
Cosmetic issues
Excel 98 export
Chart IO
Applix export
Sheet object hooks to scripts
Shared whiteboarding

Work to be done / in progress
MVC split & componentization
more Gnome Basic interfaces
more chart types / integration