(Notice the irony in the title of this post...)
In response to a comment on the last post, here's how I might retitle parts II and III of the Back to the Future films:
Escape from the Future
Back to the Ranch
The Rambo films had an odd titling sequence. The first film is First Blood, followed by Rambo: First Blood Part II, followed by Rambo III, followed by Rambo.
Blood of Patriots (the ham-handed flag-waving and violence in this film has to be seen to be believed - I think this title really suits it)
Last Blood (I haven't seen Rambo, but judging by the previews, this film looks bloodier than the first three films combined. Last Blood gives the film the ghoulish finality I imagine it needs.)
To be fair, there are plenty of good sequel titles out there. I was quite tickled by the irreverent Live Free or Die Hard, and I've always loved Scream, Blacula, Scream.