Yes, I really liked the way ebay did it. And I really think it's worth the extra coding needed in order for it to work. It's a handy tool!
And normally you wouldn't "forget" you username, but if you're like me having dozens of website that your registered on and also with different usernames (big sites = most "known" usernames already taken :D Therefore need to either have a unique name that no one will ever figure out... or you will need a different name than the one you use usual.) it can actually be easy to forget that name once in a while ;)
Also, security protection on the whole "Forgot my password/username" thing is important. Else robots could try to abuse the system.
I'm forseeing (?) three options:
1. CAPTCHA images after three failed attempts.
2. Security question after three failes attempts.
3. After three failed attempts, block user for X minutes (requires extra db field to store the timout in).
4. A combination of one or more of this suggestions.
I love your work, -borg-!
Cheers