Denver, CO - Nothing. Colorado Public Radio's incarnation of KVOD is next door at 88.1.
Oakland, CA - Nothing, usually. Superpower KQED-FM is next door at 88.5. KECG from El Cerrito might occasionally make it through but its 60 dBµ barely reaches Berkeley.
Historically - Just before I started volunteering there, the student station at the University of Missouri, KCOU, changed frequencies from 88.3 to 88.1 in order to get a power increase from 10 to 430 watts. This would have been around 1976 or 1977. KCOU had a stroke of luck in that KMOS-TV in Sedalia, Mo. on channel 6 was run as a fairly low-power operation since it was co-owned with KRCG-TV in Jefferson City. The channel 6 signal basically covered Pettis and maybe Saline counties and that was it. The whole point of that arrangement was to keep a third network affiliate on VHF out of the central Missouri market. KMOS-TV eventually was donated to Central Missouri State University in Warrensburg to become a PBS member station (yes, from CBS to PBS); when it finally went full power late in 1979, the Columbia cable system had to run the signal through multiple filters to reduce interference from KCOU. If KMOS had been full-power in 1976, KCOU would never have gotten any kind of power increase or might not even have existed at all.