V-Model (one more project lifecycle model). Steps similar to waterfall, but, unlike Waterfall, allows going back to earlier stages -- if a problem found on latest stage and needs to be corrected.
Spiral lifecycle. Was invented by a particular company in their specific project environment. As far as I know, has no wide applications in other teams.
(Russian article) Interesting idea for sustaining long projects: while working on bugs/features in a long project, you get to know its problems, deep architectural problems. So, spend some time and work on the "ideal" architecture, the one you'd build from the very beginning if you knew everything you know now. Knowing this "ideal" architecture will help you drive the project in the right direction.