This post is written as part of AOL Money & Finance's Best & Worst 2006. If you are rooting for satellite radio, cast your vote.

Back when Sirius had almost no subscribers, Sirius Satellite Radio Inc. (NASDAQ:SIRI) traded for $63. That was six years ago. XM Satellite Radio Holdings Inc. (NASDAQ:XMSR) was $45 then. But now Sirius trades at $4 on a good day and XM changes hands around $15. These businesses looked better on paper than they did once they were operating companies. XM will end the year with something short of eight million subscribers. Revenue in the last reported quarter was $240 million. Sirius had revenue of $167 million for the same period.

But it's unlikely that early investors thought these companies would have balance sheets with over $1 billion in debt, or that they would still be losing money in 2006.

To a large extent, what happened was competition. The iPod was launched in 2001, and no one thought that within five years it would sell 70 million units. The number of cars that have built-in iPod adapters grows each day -- they even put them in BMWs.

How could satellite radio investors have looked ahead and seen the cell phone as a portable music player? There are currently two billion cell phones in "circulation" and a billion more are sold each year. Nokia Corporation (NYSE:NOK) thinks it will sell 80 million music phones this year.