Gnumeric & Glom
GNumeric is not a spreadsheet program that you can safely ignore. It has many features that surpass the biggest rival in the industry, Microsoft Excel. Just to name a few, it has all the functions that Excel has plus 154 more, support for Black-Scholes formulas for derivatives, Monte Carlo simulations, 3-D dependencies. The functions that you have in Excel like Goal Seek, working with multiple sheets, autofilter, charts, cell formatting, and range naming are all present in GNumeric.
GNumeric also has support for many formats; the most popular ones being all Microsoft Excel files except Excel 2007, XML, Applixware, Lotus, OpenOffice.org and Lotus. It is also remarkable that GNumeric can output in LaTeX code. The format that the program uses is XML.
Additionally, we have batch processing options for file conversion. You do not need to open each file and save as in a different format.
The program is lightweight and works fast. You can work with GNumeric as your default spreadsheet program, but the downside is its features are not easily expandable. You have to install them via your package manager, which will also install additional dependencies.
Glom is the database application of Gnome Office. The program can be considered more of a database design. It does not have the features that OpenOffice.org Base or KDE Kexi, like having its own format for databases. This is a two-sided issue, Glom uses the most powerful database in the world, PostGresql, which is incredibly good; on the other hand it can not work on databases it did not create.
PostGresql, in my opinion, is not a simple toy that you can go and play with. It rather requires a good working knowledge of databases. On the other hand, if you know what you are doing, your database is virtually unlimited; you can create any database of any size that serves your needs.
Speaking about the back-end issues of PostGresql, a subset of its basic features are presented to the user with a graphical user interface. You can create relationships between tables, create index, search, and report inside Glom without knowing any of the PostGresql commands. However if you want to go one step further for calculated fields, then you might need some coding with Python.