The NYSE periodically lists the top 100 open short positions. This list is interesting because it shows which companies the market believes are overpriced.
Sadly, the NYSE list only shows total shares sold short, not what percentage of shares outstanding these are. The handicap is obvious: it's hard to compare companies and to gauge just how much short interest there really is. One needs to look at the short interest as a percentage of the shares outstanding.
Another interesting metric is to look at the days-to-cover number. As it says, this number indicates how many days it would take for short sellers to unwind their positions. This number is interesting both as a short seller perspective and as a contrarian one. It shows how willing short sellers are to short the stock given the danger of a long and painful short squeeze.
Perhaps the product of both numbers is even more interesting to look at since it combines both equally.
A word of caution though is to be careful when shorting low-priced stocks, since they tend to be more volatile and show larger swings, forcing a short seller into margin calls and big losses.
Without further ado, here's the list, with the extra fields mentioned above added.
(if the table doesn't load, click here)