http://www.nimnak.com/index.html

It's a small agency, but IME all the staff are very diligent and all are competent English speakers. (English of the Strine strain mostly - but that's never been a problem for me). They have sometimes been creative enough to find attractive alternatives to the flights that I looked up on my own and they have taken the trouble to remember my quirky preferences and such details that set good travel agents apart from computers.