I've got an idea. If she's struggling with more than one choice, post it and we'll give our opinions. She's going to want to own the design, don't you think? That's a cool machine, but not very avatar-ish, 'cause it's hard to make out that small.
Have you talked this over with her? So your avatar and handle reflect the fact that you're a red-headed electrician, if I recall correctly. Maybe she'll want to come up with something that reflects what she does or is interested in. But if she chooses a picture of Brad Pitt, you're in trouble.