I now work on linux machine that I don't have admin on, so I can't install dropbox. is there any way to download some files from dropbox (by WWW) ?
Yes, of course. Just login (right-top corner.. kinda hidden) at the Dropbox site and there you go.
(You only need a browser, no plugin, no installation.)
As mentioned in other answers, you can simply log in to your Dropbox from their website interface.
Alternatively, if you place files in your "Public" folder, you won't even need to log in. You can access the files directly. All you have to do is get the direct link to the file by right-clicking it. This page explains how.
You can just log into the dropbox website and view and download your files there.