A few comments
This looks good. For list structures, I think it's probably a good idea to focus on the basic variants first: singly linked lists, doubly linked lists and circular (usually doubly linked) lists. The optimizations you mention probably belong in separate articles. In the case of balanced trees, you probably ought to talk about some of the standard variants (red-black trees, 2-3 trees and 2-3-4 trees). If you do include B-trees, you should probably mention that 2-3-4 trees are the simplest non-trivial B-trees. You might also talk about the relationship of red-black trees and 2-3 trees (which are largely equivalent). Did you mention heaps? I may have missed it. In any case, thew two most standard variants are the binary heap and Fibonacci heap. When talking about graphs, do not forget directed graphs (digraphs) an the important case of directed acyclic graphs (DAGs). Another important topic for (general) trees is traversal strategy (depth first or breadth first). Trees and lists are, of course, examples of recursive data structures, and you might want to say something about recursion, though detailed treatment really belongs in another article.
Okay, enough of my rambling! Nice work. Greg Woodhouse 22:58, 20 August 2007 (CDT)