Osman Rashid, who co-founded online textbook rental firm Chegg, has raised $7.5 million more for his new stealth electronic books startup Kakai; we reported in August that the startup had raised $1.1 million. The new money comes from a roster of big name investors, including Andreessen Horowitz, Josh Kopelman of First Round Capital and serial angel investor Ron Conway.

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Still no details on what exactly Kakai will sell—or rent. Over the summer, we had reported, based on trademark filings, that Kakai was possibly developing a new e-reader, although Rashid told us then that the company was “really more of a test bed to try out apps for devices like iPhone, Pre and G1/G2” and “that is where the device bit in (the trademark filings) is coming from.”