GnuCash is a personal and small-business financial-accounting software package that's also available for Linux, Mac OS X, and Windows. Both powerful and flexible, GnuCash lets you track bank accounts, stocks, income and expenses. As quick and intuitive to use as a checkbook register, it is based on professional accounting principles to ensure balanced books and accurate reports. Among GnuCash's key features are double-entry accounting, small-business accounting, invoicing and more. Data can be imported from programs such as Microsoft Money and Quicken, while it can be exported to spreadsheets such as Microsoft Excel. Once again, this free software's interface is so intuitive and familiar that if you've used other accounting programs before, this one will be no problem.
3. Desktop publishing: Scribus
Scribus is a free program that offers professional page-layout capabilities for Linux, Mac OSX and Windows desktops. Scribus supports professional publishing features including CMYK color separations for both press-ready output and PDF creation. I've found the software can do just about anything the paid packages can, and it's comparable to InDesign or Publisher, for instance.
4. E-mail: Zimbra
Zimbra Desktop is free e-mail and calendar software that runs on any Linux, Mac or Windows computer. The tool offers e-mail, contacts, calendar and document capabilities all in one application, and it lets users read e-mail from any POP or IMAP e-mail account, including Gmail, Hotmail or business e-mail. Owned by VMware, Zimbra works both online and off, and there's no limit to the size of your e-mail storage. As an added bonus, it's also available in 20 languages.
5. Web page editing: KompoZer