Pen name for traditional publishing (some day, I hope) is Libbie Hawker. Libbie is my real first name; Hawker I picked because it fits with Libbie better than my real last name, and is easier to spell and pronounce and remember than many other options as well.
Pen name for my self-published experiment in fun is Lavender Ironside. It came to me one day (mostly because I know a lady whose real first name is Lavender), and it sounded like a totally great pen name for historical fiction: it's memorable, it's a little kooky, and it sounds like a dusty old historian. Since I don't mind much whether my historical fiction ever takes off, I figured I could use a fun, throwaway pen name on it.