Heat Guy J - Hugely Improved art and animation compared to TV
Ergo Proxy - Very improved art and animation, and additional scenes in the final episode
Arjuna - Each episode was considerably longer on DVD than on TV broadcast, with some episodes being 30+ minutes
Kamichu - Each episode has additional scenes not seen on TV (some episodes close to 30 minutes) and 4 additional episodes not seen on TV
That's just some.