When you know what you want, your best bet's a specialist: if you need a bed, go to Sleepy's, and if you need "Beyond", go to Bed Bath & Beyond, and just try to ignore the beds and baths. When what you want's a condo, go straight to CondoDomain.
Based in Boston, pointedly named brokerage CD just grew to include San Fran, vying to be your online hub for finding condos -- and nothing but the condos -- by coupling a slick search engine with personal agent care to assist you all the way to closing. Start by studying CD's Gmap of on-the-market properties (populated by MLS data, new construction developments, foreclosures, etc), which upon mouse-hovering'll pop up exterior snap shot/price range/# of units; click "view full details" for a Google Street View, a Walk Score, and a physical/historical building descrip (if it reads "lubricated", you added an extra "m" to the url). The next step: opt for "Full Service", and you're paired with an actual live local agent to help scout/compare properties, or go it alone and arrange tours yourself; either way, CD handles final paperwork & negotiation, and at closing'll return either 20% of the commission (for "Full Service") or 90% if you found the place yourself -- money you'll need to drink away the fact that your walls are actually made of rats. Mean, horrible rats.
CD also informs buyers with a blog about the SF condo landscape, which analyzes market trends, specific properties, and neighborhoods -- over-educating you to the point that you'll burn out on condos, and settle for Bed.