Unfortunately, I can't find anywhere on Apple's website to provide recommendations/bug reports on their software. If anybody knows where I can send this message, I'd like to hear. This recommendation is for Preview (which I like much more than Adobe).
1) I recently upgraded to 10.5 from 10.4, and I like some of the new features in Preview, especially the highlight function. However, many of the science papers I read are so old they were not OCR'd; they're just images, so the highlight function is disabled. I still want to be able to highlight though. I would imagine a click-drag rectangle with ~75% transparency would work just fine.
2) Similarly, most science papers are written in 2 columns, but Preview doesn't notice this. Instead, it selects text from both columns. So perhaps there's a better way to handle highlighting.
3) When I open up a paper from thar interwebs, I usually like to save it to the desktop, and organize my pdfs later. However, Preview always wants to save it to Documents. I think it would be better if the default save folder was equal to the last folder. This is obviously a minor detail.