Other
University of Leicester: Irregular Galaxies
Provides a general overview of irregular galaxies, including a specific look at type I and type II irregulars.
PBS
Pbs: Nova Online: Galaxies, Clusters, and Superclusters
PBS site explores these building blocks of the universe as well as their various types and clusters.
Space Telescope Science Institute
Nasa: Hubble Space Telescope: Universe
At this site from HubbleSite you can discover the universe by taking a look back toward the beginning of time. Site contains links to information on planets, stars, galaxies, and much more.
Other
Sky Server: Galaxies
SkyServer explains and presents images of spiral galaxies, elliptical galaxies, irregular galaxies, galaxy clusters, galaxy collisions and the like.