My total seems to stay about the same all the time - I give it away almost as fast as I get it 
EDIT: Well, I did spend several hundred million on the Invention system badges and IO sets when they came out, but after that, it kinda stabilized 
@Golden Girl
City of Heroes comics and artwork
Probably about 25-30 million, which I promptly spent on some IO sets.
1,894,000,000 When i was moving stuff from US to EU