There was one called the Blitz chip which was very simple and effective but its not sold anymore.
Something to bear in mind:
Out of those mentioned in this thread, the Hyperdrive and Virtue are viewloader approved.
Which means they wont void your warranty.
Gangstar, one of the oldest and most popular vlocity chips, is still yet to achieve viewloader approval.
Their marketting is all about Pazownzing nooblets with breakout modes so I guess their target market doesnt mind the odd hopper fire.
