This paper describes a creative alternative for topic modeling: mixed-membership on a "counting grid." The advantage of this approach seems to be that you can move smoothly across the grid, achieving a
high effective number of topics while the spatial smoothing prevents overfitting. The disadvantage seems to be that there are more parameters (grid dimension and size, and window size). A variational inference procedure that is somewhat to LDA is possible, although no speed/complexity comparisons are provided. The spatial nature of the approach has potential advantages for visualization as well.