AFPEX also has no geographical restrictions, but to get the login you need to be UK resident.
I use both Afpex and Homebriefing.
Afpex is quite nice in the speed with which you get the ACK upon filing an IFR flight plan - a second or two. HB takes 2-5 minutes, presumably because somebody has to okay it.
Homebriefing is much more user friendly, but is not free.