There are many research oppurtunities in EM. Consider any facet of clinical care and try to apply it to an EM setting (ex: the utility of blood cultures in the ED). There are also many clinical aspects of medicine unique to EM, which can be investigated as well (Bedside Ultrasound in the trauma paient). From the hospital-management side of things, studies that involve the increasing senior citizen population, overcrowding and patient flow, 72-hour returns, etc. are always being looked at the help shine light on ideas that may improve the efficiency of EM management.
Try looking at a copy of the Annals of Emergency Medicine or the SAEM publication "Academic Emergency Medicine" to get some more ideas.
Basically, the sky is the limit, especially if you can find ways to make standards of care more efficient and cost-effective.