San Francisco - Yoono, the developer of a social Web browser extension for Mozilla's Firefox, has added $4 million to its first round of venture capital financing, which was led by AGF Private Equity, TechCrunch reported.

Los Angeles - The Mozilla Firefox Web browser, an open-source alternative to competitors such as Microsoft's (NASD: MSFT) Internet Explorer, Netscape Navigator or Apple's (NASD: AAPL) Safari, has now been downloaded over 500 million times, according to a note on SpreadFirefox.com. The browser passed 400 million downloads in September 2007. Firefox now commands about 17% of the browser market, and 28% of visitors to NYTimes.com in February were Firefox users, according the paper's Bits blog.

Boulder, Colo. - Me.dium, a developer of technology that connects users who visit the same websites, announced on Monday that it has raised $15 million in its second round of venture capital financing, led by Commonwealth Venture Partners.

Santa Ana, Calif. - Cluepedia, the developer of an extension for the Firefox Web browser that lets users rate websites and products and share their reviews with others, has raised an undisclosed sum from a group of 45 angel investors, socalTECH.com reported.

Cambridge, Mass. - Red Swoosh, a provider of content delivery technology that was acquired by Akamai several weeks ago, has released a BitTorrent file-sharing client for the Mozilla Firefox browser, TechCrunch reported. FoxTorrent allows users manage torrents and download various media files from the BitTorrent peer-to-peer file-sharing network, as well as stream files as they are downloading.