If you google on ‘papers’, the first hit you’ll get is
http://mekentosj.com/papers/: linking to mekentosj’ Papers program. The fact that it is the first hit on google shows that it is a popular program — or at least that a lot of sites link to it. Still, for the people who don’t know about it, I think it deserves a little more publicity.
Papers is basically a library system for scientific publications, it’s often described as iTunes for scientific papers. What it does is giving you a central place to store your pdfs, and making it easier to look through them — just as in iTunes you can make folders and smart folders; pdfs can appear in multiple folders. Thus, if you make a smart folder on multitasking and one on cognitive models, a paper on a cognitive model of multitasking will appear in both folders. You can also view your papers by author or journal, and in that case Papers immediately shows you the last articles published by the author / in the journal.
Not only does it keep your pdfs organized (also on your harddisk, in a folder structure of your choice), it also lets you search in a couple of popular search engines from within the program (pubmed, scopus, citeseer, google scholar and more). Of course, it also has a couple of standard features, like actually reading the papers (full screen if you like), printing them, sending them by email, and opening them in external viewers, like preview.
So, if you’re pdf’s are piling up around you, having names like sdarticle.pdf or 1191.pdf, give papers a try!