Opera has a greedy cache system! After 6 months of using it, I had accumulated 5.6 million cached files that consumed 350 MB of HD space. When I tried to delete them using the trash, my comp crashed because it could not handle the files. I had to delete them immediately by trashing Netscape's cache and then dragging the Opera cache folder to the trash at the same time. It presented the "delete immediately?" dialog box, so I pressed OK and the hour-long process ensued. I got my space back, plus I figured out why my comp crashed during a desktop rebuild, it couldn't handle all the files.