Is b.ing already taken? If not, buy it ASAP!
Edit: I kind of get it with .com domains, but all TLDs?
You might win in court/arbitration if you have a legitimate reason for owning the domain, but you're going to need deep pockets to pull it off and be willing to put up with the harassment of a company that has infinity money and wants to crush you for sport.
You could not run an auction site as ibay.com
But you could still use the string in another context. e.g. eBayern
(Bayern=Bavaria)
This sentence alone increases my adrenaline level. The brainless arrogance of a pack of overpaid lawyers.