Metallicity: What are the metallicity values of various galaxies?
metallicity is a complicated issue, and giving just one number (usually Z, but also 12+log(O/H), ...) is very rough. But, here are the standard values for the Magellanic clouds:

LMC: Z~1/2 

SMC: Z~1/5

with Z=1 being the solar value. Practically, the values will vary across any given galaxy (the Milky Way also has a metallicity gradient). 

Reference: 

Madden et al. 2014, PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF THE PACIFIC, 125:600–635, 2013 June
http://adsabs.harvard.edu/abs/2013PASP..125..600M

The article is also available on astroPH