  We present high-resolution UV spectra of absorption-line systems toward the
low-z QSO HS0624+6907 (z=0.3700). Coupled with spectroscopic galaxy redshifts,
we find that many of these absorbers are integalactic gas clouds distributed
within large-scale structures. The gas is cool (T<10^5 K) and has relatively
high metallicity (Z/Z_sol>0.9). STIS data reveal a cluster of 13 HI Lyman alpha
lines within a 1000 km/s interval at z=0.0635. We find 10 galaxies at this
redshift with impact parameters ranging from 135 h^-1 kpc to 1.37 h^-1 Mpc. We
attribute the HI Lya absorptions to intragroup medium gas, possibly from a
large-scale filament viewed along its long axis. Remarkably, the metallicity is
near-solar, [M/H] = -0.05 +/- 0.4 (2 sigma uncertainty), yet the nearest galaxy
which might pollute the IGM is at least 135 h_70^-1 kpc away. Tidal stripping
from nearby galaxies appears to be the most likely origin of this highly
enriched, cool gas. More than six Abell galaxy clusters are found within 4
degree of the sight line suggesting that the QSO line of sight passes near a
node in the cosmic web. At z~0.077, we find absorption systems as well as
galaxies at the redshift of the nearby clusters Abell 564 and Abell 559. We
conclude that the sight line pierces a filament of gas and galaxies feeding
into these clusters. The absorber at z_abs = 0.07573 associated with Abell
564/559 also has a high metallicity with [C/H] > -0.6, but again the closest
galaxy is relatively far from the sight line (293 h^-1 kpc).
