An approach to Project Management (and the tool to implement it), where the entire process is completely transparent, and all the decisions are made by team itself.
(Russian article) Raises a valid question: how do we statistically interpret PERT deviation? Can we use it to estimate confidence level? Author thinks it is too much inaccurate, from pure statistics point of view. Proposes alternative approach (based on 2 point estimations, min & max, and Normal distribution.
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.