  We conduct an ultraviolet (HST and FUSE) spectroscopic survey of HI (Lyman
lines) and seven metal ions (OVI, NV, CIV, CIII, SiIV, SiIII, FeIII) in the
low-redshift intergalactic medium (IGM) at z<0.4. We analyzed 650 Lya absorbers
over redshift pathlength Delta z=5.27, detecting numerous absorbers: 83 OVI
systems, 39 CIII, 53 SiIII, 24 CIV, 24 NV, and so on. Our survey yields
distributions in column density and estimates of the IGM baryon content and
metallicities of C, N, O in the IGM. In the low-z IGM, we have accounted for
~40% of the baryons: 30% in the photoionized Lya forest and 10% in the
(T=10^5-6 K) warm-hot intergalactic medium (WHIM) traced by OVI. Statistical
metallicities of C, N, O ions are consistent with the canonical (z=0) value of
10% solar, with considerable scatter. Improved statistics for weak OVI
absorbers allows us to estimate Omega_WHIM/Omega_b=0.073+-0.008 down to
logN_OVI=13.4. NV absorption is well-correlated with OVI and both ions show
similarly steep power-law indices dN/dz N^-beta with beta_OVI beta_NV 2 while
beta_HI=1.7. We conclude that OVI and NV are reliable tracers of the portion of
the WHIM at T=10^5-6 K. CIV may be present in both collisional and photoionized
phases; N_CIV correlates poorly with both N_HI and N_OVI and
beta_HI<beta_CIV<beta_OVI. The ions CIII, SiIII, and SiIV are well correlated
with HI and show patterns typical of photoionization. Adjacent ion stages of
the same element (CIII/IV and SiIII/IV) provide useful constraints on the
photoionization parameter, logU=-1.5+-0.5. Comparison of SiIV and CIV with
high-z surveys shows a modest increase in line density, consistent with
increasing IGM metallicity at recent epochs.
