Hasse diagram graphics package?

[Robert Levine]

I am putting together some materials for a future course that will
involve a certain amount of introductory lattice theory and would
really appreciate finding out if there is some kind of LaTeX utility
along the lines of Chris Manning's AVM program which would make it
relatively easy to produce Hasse diagrams. Ideally it would be
something where the user has the option of annotating nodes with
algebraic expressions of reasonable complexity. If you've heard about
such a thing, *please* let me know---

thanks very much,

Bob