As it marked the 75 millionth download of its Firefox Web browser, the Mozilla Foundation said it was expanding in several directions. The foundation's open-source e-mail reader, Thunderbird, is approaching its 10 millionth download. Mozilla's browser for small devices, Minimo, reached a milestone, as a prerelease version appeared with tabs, a bookmark manager and RSS feeds. The Mozilla staff itself has quadrupled during the past six months, to 40 employees. "We're beefing up the management on the project," said Chris Hofmann, whose title at Mozilla is in flux since the foundation hired another director of engineering. "The project is still...