I didn't know the answer to this offhand when I clicked reply, so let me steer you through the logic to find something like this.
First, there are really only two registry hives that you should even *think* of messing with: HKLM and HKCU. HKEY LOCAL MACHINE contains settings that are machinewide, and HKEY CURRENT USER contains user-specific settings.
In our case, each user who uses IE gets a personalized list of previously visited websites. So we know right off the bat we want to start looking in HKCU.
I have enough experience with the registry that I knew I could immediately go to Software\Microsoft\Internet Explorer, but I think that with a little searching, most people would end up there.
Aha! Under that key is another key, "TypedURLs" that contains the list of typed URLs! 🙂
The acronym "MRU" is short for "most recently used" and is sprinkled throughout the registry. That can be helpful to search on as well.