I'd also be interested in general tips, exercises, etc on improving speed/accuracy.  I seem to have hit a wall around 110-120wpm.

I had the chance to try out Amphetype this afternoon, and it's pretty close to what I'm looking for (can create lessons to target problem words/letters).  The problem is, practically all the proper nouns would be considered problem words; lessons for letters require spaces between each letter, rather than typing words containing those letters; and doing those targeted lessons increases the "missed" count for those words, so they'll always show up as problems.  Perhaps I just haven't figured out how to use it properly yet...

Tried Rapid Typing; didn't like it.  Typing Master sounds better than Typing Tutor 7; I'll check it out.
I'm not sure Typeracer's Sudden Death mode actually helps you improve.

Thanks!

You'll want to make a list of words for Amphetype, not letters. You can have it create a problem word list based on your typing so far but as you say it'll contain a lot of "special" words like Alice, Tweedledum, Tweedledee, Queen... ;) You can clean up that list and submit it as a lesson to get exactly what you want/need. Amphetype is very flexible once you get used to it!