Good question...
I actually purchased this name initially since it was the abbreviation for Homework. Once parked, I noticed significant traffic. Although it may be a typo, I haven't figured out what officially. A while back, I thought it might have been associated with an ex-public company named Hotelworks given their symbol was hwrk. This domain has never really convereted well using keywords: homework, student loans etc. MTD, it has earned approx. .58 on 5 clicks. I haven't yet found the optimal keywords to use with this one.