Five of my Bettas got their names from their colors. Rosso is an Italian male name for Red, Aurora because she has very vibrant colors, Akane is Japanese for deep red and the name of a anime character (got it off a link that someone posted, Thanks!), Princess Peach who was almost pinkish in her color, then Princess Daisy who is orange. You can also say that 3 of those names were inspired by either a video game or anime that I liked.
Poseidon was named after the Greek God of the Sea. Finally, Big Momma originally had a color based name but I didn't feel it fit her. She just looked like a Big Momma. Don't ask me to explain how she looks like a Big Momma, she just does.