The Virtual Goods Summit was held at Stanford last week. The summit showed how flexible a virtual good can be; it's hardly all about buying a new staff in World of Warcraft, reports GigaOM.

Among the highlights of the summit was news that virtual goods is "easily a billion dollar market," according to virtual currency exchange site Sparter. Virtual world Gaia online has 50,000 completed auctions daily, while casual MMO Puzzle Pirates earns the majority of its $350,000 revenue per month on virtual sales.

And its not just virtual worlds. Sites like Facebook and Hot or Not allow users to buy items like virtual flowers for a crush. The flowers take the shape of an icon that is then posted to the recipient's profile.

In China, firm QQ, the mainland's largest IM/games/social network, sells virtual penguins as pets - and 54 million have been sold so far.