Word classes mindmap
For a list of Roget thesaurus categories assigned to gismu see here
Another thesaurus-like dictionary is the list of oblique places by Colin Fine and Nora LeChevalier.
Evgeni Sklyanin's gismu thesaurus: TeX file (local copy) and HTML file
Above HTML link is defunct. (2003.5) I found HTML on xod's page and one one with Hanja. mi'e sanxiyn.