Obviously, realtors, like myself have access to MLS data for previous sales for SF neighborhoods. I'm a data junkie, so I like to look through various information on sales, days on market, etc. when researching for clients or myself. I'm also a big fan of socketsite.com which has some great data and trends. The Tax Collector and Treasurer's office on sfgov.org may also provide some information. I like AlstosResearch as well. Here's a link: http://www.altosresearch.com/research/CA/SAN+FRANCISCO. Finally, Inman News is a good source, but may not be as micro as you'd like. Here's the link: http://www.inman.com/. Of course, I'd be happy to help if you'd like.