Morrison

90% T-Bills/10% Berserk and Other Intriguing Portfolios

It's different than being on margin, as the risk is far less (no margin calls), and the there is no interest charged on the borrowed money. You pay the fund expense fee (generally 1.5% / year), but thats it.

I'd be interested in responses to Locke's question regarding holding a double long fund to an extended period vs the underlying index (eg. DDM vs DIA or SSO vs SPY).