Project Lead: Developer mailing list.
If you're looking for user information about Calc, try these links:
Submit an Issue
If you found a bug or want to suggest an enhancement, find the information about submitting issues in the QA project.
In addition to general extension development, Calc supports the use of Add-In components to extend the set of functions that can be used in cell formulas. Add-Ins can easily be created using the Add-In Wizard of the NetBeans integration. Besides that, some articles are available:
Specifications for some spreadsheet features
See also the “Documents & files” link to the left of this page.
To see what the Calc team at Sun is doing, look for the weekly update entries in the GullFOSS blog.
Currently, the major topics of Calc development are:
Excel 2007 import filter
The import filter for Excel 2007 files is continually improved. For details about the filter implementation, see its wiki page.
ODF formula specification
Within the OASIS OpenDocument Formula Subcommittee, a specification for spreadsheet formulas is being created. Necessary changes are being implemented.
Integration of R into Calc
A Summer of Code project has integrated the R environment with Calc, see the page in the wiki. The Summer of Code project is completed, but the integration will continue to be improved.
There's a separate wiki page about our usability activities.
These are some areas where help would be useful. Well thought-out patches are welcome, but please file your Joint Copyright Assignment (JCA) first, see How to submit code to OpenOffice.org.
Statistical data analysis tools (ANOVA etc.), see issue 4921.
Leonard Mada has posted some code for ANOVA to the sc-dev mailing list.
Component to check spreadsheet documents for potential errors
Write an extension that checks a spreadsheet document for potential errors in formulas, presents a list of the findings to the user, and allows to correct them. Note that the conversion of text to numbers is already handled by the CT2N extension.
A Watch Window to watch certain cells
A Watch Window is a separate, small window that remains "on top" and enables users to monitor a selected set of cells, see issue 28386. This could possibly also be done as an extension.
CSV import enhancements
Add new spreadsheet functions and parameters according to ODFF
The OpenDocument Format Formula specification (ODFF aka OpenFormula) defines several new spreadsheet functions and new optional parameters to already existing functions that have to be implemented.
See also the list of suggestions for the Community Innovation Program.
These are issues that someone new to the project might want to look at. They generally don't require very deep insight into the inner workings of Calc.
These are issues where help is needed.
This is a long list, sorted by priority and votes. Some of these may currently be blocked by other issues.