Tacit Knowledge Systems announced Tuesday that it raised a $10 million third round of funding, led by Alta Partners. Previous investors Draper Fisher Jurvetson and RVC Greenhouse Fund contributed to this round. Palo Alto, Calif.-based Tacit has raised a total of $21 million. Tacit develops software designed to automatically identify experts within a company's work force on various topics from vendors to databases. The software searches through such information as employees' outgoing e-mail to transferred files, using key words to identify workers with the most knowledge in a particular field. See complete list.