  (abbreviated): This paper presents the results of a high resolution radio
imaging survey of all known (96) low-luminosity active galactic nuclei (LLAGNs)
at D<19Mpc. We find that almost half of all LINERs and low-luminosity Seyferts
have flat-spectrum radio cores when observed at 150mas resolution. Higher
(2mas) resolution observations of a flux-limited subsample have provided a 100%
(16 of 16) detection rate of pc-scale radio cores, with implied brightness
temperatures > 10^8 K. The five LLAGNs with the highest core radio fluxes also
have pc-scale `jets.' Compact radio cores are almost exclusively found in
massive ellipticals and in type1 nuclei. The core radio power is correlated
with the nuclear optical `broad' Halpha luminosity, the nuclear optical
`narrow' emission line luminosity and width, and with the galaxy luminosity. In
these correlations LLAGNs fall close to the low-luminosity extrapolations of
more powerful AGNs. About half of all LLAGNs with multiple epoch data show
significant inter-year radio variability.
  Investigation of a sample of ~150 nearby bright galaxies, most of them
LLAGNs, shows that the nuclear (<150mas size) radio power is strongly
correlated with both the black hole mass and the galaxy bulge luminosity;
linear regression fits to all ~150 galaxies give: log P(2cm) = 1.31 log
M_blackhole + 8.77 and log P(2cm) = 1.89 log L_B(bulge) - 0.17. Low accretion
rates are implied in both advection- and jet-type models. In brief, all
evidence points towards the presence of accreting massive black holes in a
large fraction, perhaps all, of LLAGNs.
