If there's somebody on your review site, who ranks highly several of my highly ranked coffee shops, and ranks low a subset of my lowly ranked coffee shops, I'd be much more prepared to consider their other coffee shop reviews as relevant to me. Even better, location based services like 4Square of Facebook checkins could expose their "revealed preferences" to the algorithm as well, someone who rates Fourbarrel and Ritual highly, but checks in to Starbucks four times a day is less likely to be someone who's reviews I'd want to read than someone who perhaps rates Fourbarrel and Ritual lower on an absolute scale, but checks into both regularly as well as, say Sightglass and BlueBottle.
I'd really like a time and event aware as well as just venue aware review function. Zeitgeist on a Thursday night, or after a critical mass ride - is a _vastly_ different experience than Zeitgeist on a sunny Saturday afternoon when it's full of slumming sunset and marina crowds. DNA Lounge really needs separate review categories for Death Guild nights, Bootie nights, and out-of-town dubstep artist nights - people who love (and hence rate highly) one of those events are significantly less likely to enjoy the other two as much - which makes a Yelp-style single rating for DNA Lounge not particularly useful.