If you regularly read journal Table of Contents pages and want an easy way to keep track of papers you find interesting, you may want to try my "Add to Connotea" Greasemonkey script.
To use it, you first need to have a Connotea account. When you navigate to a journal web page for the first time after you have started your browser, you will need to enter your Connotea username and password.
The script adds an "Add to Connotea" link next to every DOI on journal pages. If you click on this, a dialog box appears that allows you to bookmark the paper on Connotea. A useful feature is the ability to quickly select from tags that you have already used. The "Add to Connotea" script also displays a count of the number of people who have already bookmarked a particular paper. If you click on this number, it will bring you to the Connotea page for that paper.
Why use Connotea inside of just bookmarking a paper, or saving it on your computer? Here's why I do: adding to Connotea is 'cheap'. I'm a lazy bookmarker; now that my bookmarks have reached the bottom of the my screen I've given up. Arranging into folders is too much hassle for my busy lifestyle. Now I can tag a paper with "Read me later", or "Journal club", and I will actually be able to find them later. Bookmarks are available from any browser; you can bookmark from home, and read the paper later from work. Your computer may explode (not due to my Greasemonkey script, I hope), but your bookmarks will still exist. Another nice thing is that Connotea is part of Web 2.0 - it provides an API that allows it to be used in mashups; like this Greasemonkey script!
There is also the 'social' side to 'social bookmarking'. I have already mentioned that the "Add to Connotea" script keeps a count of how many people have bookmarked a particular article; this may indicate that a particular article is worth reading. There are people who track all articles posted with particular tags, e.g. "evolution", to keep up to date with the latest articles, but I'm not sure how useful this is in chemistry. Also, you may want to keep up to date with what all the kool kids are reading, in which case you may want to track what articles your friends are bookmarking (note: all bookmarks are generally public, but you can opt to make them private). Connotea allows you to add a description and/or a comment to an article, but while this seems like a neat idea (e.g. for posting a reviews), it does not seem to be used that much and in fact, seems to suffer from link spam (see here).
I should point out that Connotea also provides a bookmarklet that you can click after selecting a DOI. While the bookmarklet is the only option for websites that my Greasemonkey script can't handle, I find my script a handier way to bookmark papers on journal websites, plus you have the added goodness of identifying popular articles.