Ad network ARPU Inc. has raised a $8.73 million third round from Grotech capital, along with previous backers Polaris Venture Partners and New Atlantic Ventures, according to TechJournalSouth, citing regulatory filings. Last year, the Washington, DC-based company raised $5 million from Polaris, Grosvenor, New Markets and Draper Atlantic. The company delivers ads that run pages on where users are buying a product—hence the name. So if someone is buying a disk drive, per their example, they might see an ad for anti-virus software running next to it. Customers include ISPs and online retailers. (via VentureBeat)