Available in different sizes for the iPod nano 4G ($20) and iPod touch 2G (TBA), Speck's new PixelSkin is based heavily upon the same-named case for the iPhone 3G, and its ArmorSkin predecessors for earlier iPods. Distinctive is its wraparound blocky rubber texture, which stops at the face and leaves holes for the screen and controls. Sadly, no screen protectors are included with these cases. Speck is offering the iPod nano version in 9 different…