The only problem would be quickly locating the one you want when the list starts getting unwieldy long. But Firefox 3.x stores bookmarks in a database, so there should be little performance hit no matter how many sites you have bookmarked.
IS having a long list of Book marked sites A Bad Idea? I tend to book mark many useful sites I find** and end up with a long list in firefox
so I can just click on them is this causing any problems? and if so what's the alternative?