One good example of CRG work is css_imgtext by Ernesto that is already incuded into the CORE for 4.0! Lately (2009) Ernesto has created the single image without the tagsoup for TYPO3 4.3. Susanne split the different css styled content parts according to their version, so only the appropriate part of css_styled_content is loaded. JoH did a nice fancy corners extension: typo3.org/extensions/repository/view/fancycorners/ and Sacha was the originator of the cleaned up output of TYPO3.
The Content Rendering Group has formulated the following goals:
For starters I would want to offer you the benefits of getting your output XHTML compliant. The New York Public Library has an excellent styleguide and a specific part on XHTML benefits: