saving a PDF file
The recent version of Zotero (3.0 beta) adds to the Firefox download dialog an option to "save to Zotero". This is a nice addition that helps to overcome some problems with certain site translators. However, the file is saved to the current collection, while, in my opinion, it is more reasonable to save into (as an attachment) the current item.
I generally think that Zotero should be careful with attaching automatically because once that's done it's going to be hard to find an item (whereas you can easily find new single items using date added).
Unless you have done so already, please report "Some problems with certain site translators" in a new thread.
P.S.
The problematic site translator is "Optical Society of America". The site has changed its design and now it opens another (annoying) page when you try to download a PDF. It seems to fool the translator. I reported it, but got no response. In the past I fixed several bugs within this translator, but at the moment I just have no time to that. Will probably fix it in a month or so.