Persephone, a Fairy character who sells upgrades in the Activision computer game Skylanders: Spyro's Adventure (game)

"From that we can make money," he added, alluding to the company's on-line storefront, which sells accessories, software, upgrades and Web-based tutorials.

On its website, Lodsys claims ownership of patents related to technologies that "provide for online purchasing of consumable supplies," and "sell upgrades or complimentary products," among others.

While selling upgrades and replacements can be a lucrative business, it means that the fast growth of the last decade might never be duplicated.

Moreover, once the customer is converted to a new product, there is the opportunity to sell upgrades later.

However, he can swim, and he can buy the skill of diving from Pierre the Merchant (who also sells upgrades).

They also help manufacturers and retailers sell upgrades or higher-end models.

Ratchet believes the company can make more profit if it stops making spare parts for older robots and focuses on selling more expensive upgrades.

He also sells upgrades that help the team in battle.

There is no money changing hands between Real and Microsoft, and the Web TV version of the player does not even present an opportunity to sell upgrades or advertising.