First off, LastPass has done a great job. Thanks LastPass team.
A feature I haven't seen but might be useful is profiles. While tags can categories information to aid in filtering and groups put sites into pseudo-containers, profiles would locate/isolate the groups. 2 examples pop to mind:
1) This could be really useful when exporting/importing. Say, I'm an sysadmin, and what to give a field technical a set of passwords --simple export a profile maintained for the field technician job role (and give it to him on a usb agent
2) Another example, would be allowing your web client plugin at PC 'A' (located at work) use only your 'work' profile while at PC 'B' (located at home) your can use all your profiles --this way if PC 'A' is compromised/you resign/is shared by others, there's no threat to your personal credentials (admittedly, logging off your LastPass plugin would keep it safe, but browser sharing coworkers wouldn't have those passwords).
Profiles would simply give you a top level drill down to 'branch' your groups.
my 2 cents and Thanks Again,