Did you know that the journal Nature (plus its myriad imprints) has rss feeds?
You can get them for Nature itself, Nature Neuroscience, and Nature Neuroscience Reviews -- plus a whole bunch more. Check out the Nature page for info. on RSS feeds and the URLs for the various journals.
A subscription is required to see most of the content, but you can probably go to your local university library or request articles through Interlibrary Loan.
See the Open Directory if you want to find a good RSS feed reader (besides the Mac’s Safari browser).