As for additional funding for research, conferences, and travel, there are three sources to which graduate students can apply:
1) MLLL provides up to $1000 per fiscal year for grad student travel.
2) The College of Arts and Sciences has a funding program as well. They provide up to $750 per fiscal year: http://cas.ou.edu/travel-assistance-program-tap
3) The Graduate College also provides funds up to $1000: http://www.ou.edu/content/gradweb/funding_and_aid/scholarships_travel_research_grants.html
Please contact the University of Oklahoma Financial Aid Services website for other possible sources of funding