  We used data from the Data Release 1 (DR1) of the Sloan Digital Sky Survey
(SDSS) in order to define a catalog of about 13,000 star-forming galaxies
(SFG). We discuss the results of two projects. First, we matched our catalog
against the ROSAT All-Sky Survey (RASS) and catalogs of pointed ROSAT
observations. We identify eight X-ray emitting star-forming galaxies; four were
known previously, e.g., the famous "most metal-poor" dwarf galaxy I Zw 18, but
another four are new identifications. The data confirm the calibration of X-ray
luminosity to a star-formation rate (SFR) by Ranalli et al. (2003), and are
used to derive SFRs for these SDSS SFGs. We also suggest two new candidate
galaxy clusters. Second, after carefully eliminating all cases of "shredded"
SFGs, we derive total absolute blue magnitudes and ionized gas metallicities
(O/H ratios). We discuss the luminosity-metallicity (L-Z) relation for galaxies
of different physical size (compact, small and large depending on Petrosian
half-light radius, R$_e$). We report the discovery of evolution in the L-Z
relation for the redshift range from 0 to 0.3, in the sense that galaxies at
higher redshifts tend to have lower O/H ratios at a given luminosity. This
evolution is strongest for large galaxies, and weakest for compact galaxies.
