Are competitors using a domain name substantially similar to your trademark for similar goods/services? You may have a great case for a domain name transfer action or cause of action for cyberpiracy, commonly referred to as a UDRP action.
UDRP or Uniform Domain-Name Dispute-Resolution Policy actions enable trademark owners to protest the unauthorized use of a domain name by a competitor or someone intending to disparage a business; resulting in the transfer of the disputed domain.
The UDRP can be applied to most generic top-level domains, .com, .net, .org, etc., and some country code top-level domains.