According to the source, snakehaven "Created Using Yahoo! PageBuilder 2.61.76" and Crested Geckos 2003 "Created Using Yahoo! PageBuilder 2.61.76".
Both of them use the Geocities supplied editors.
GeckoHaven is a different story. Clownfishie owns the site. I'm not sure what she used, but I'm guessing Front Page, or some other advanced editor. Se uses Cascading Style Sheets (CSS), which are beyond what the basic editors at Geocities can do. CSS is rather tricky to work with, but she sure got it figured out