  We report on two surveys of radio-weak AGN to look for radio variability. We
find significant variability with an RMS of 10-20% on a timescale of months in
radio-quiet and radio-intermediate quasars. This exceeds the variability of
radio cores in radio-loud quasars (excluding blazars), which vary only on a few
percent level. The variability in radio-quiet quasars confirms that the radio
emission in these sources is indeed related to the AGN. The most extremely
variable source is the radio-intermediate quasar III Zw 2 which was recently
found to contain a relativistic jet. In addition we find large amplitude
variabilities (up to 300% peak-to-peak) in a sample of nearby low-luminosity
AGN, Liners and dwarf-Seyferts, on a timescale of 1.5 years. The variability
could be related to the activity of nuclear jets responding to changing
accretion rates. Simultaneous radio/optical/X-ray monitoring also for
radio-weak AGN, and not just for blazars, is therefore a potentially powerful
tool to study the link between jets and accretion flows.
