Hi Kate.
Good luck with your search. I know there is a US law firm in Frankfurt which employs some folks who speak English only. I actually applied for a job myself, as an ex-legal secretary come office manager of Australian legal firms, although circumstances prevented me from following through.
In fact, if you have luck let me know how it goes as I will be coming over to Basel in about two years and I will be looking for an English speaking role myself. I do have some German but not enough. I'll look at legal or pharma initially, although my more recent experience is Australian government!
Cheers,
Pam