I love the name Butterbean as well, we had a guinea pig named Jemima Butterbean, known as Butter.
Delilah and Mouse were called Chu-Chu and Niu-Niu when we got them. (I'm not sure if they were spelt like that, their precious owner was from China and they meant something in Chinese.) Since we call Harley Moo-Moo, that would have been far too confusing! So in the car on the way back from getting them we were just throwing names back and forth. When Delilah came up we both agreed she looked like a Delilah. Mouse was harder to name, we almost named her Bijou, which is the French word for jewel as well as meaning tiny. After a few days though, Mouse had stuck. She gets called The Mouse, (or Da Mouse!) Mousie, Mousling, Mouzipan, Wendy Mouse etc. Delilah usually just gets Lilah as it's a bit of a mouthful, or De Lollop. Occasionally, if she has been really good, she gets Delightful. Harley is Moo and always will be