I also like her books "Morphology: A Study of the Relation between Meaning and Form" (John Benjamins, 1985) and "The Evolution of Grammar: Tense, Aspect and Modality in the Languages of the World" (University of Chicago Press, 1994).
I think her recent research interest is in the interrelation b/t grammatilization and phonology. My friend in the States told me that she gave a speech on the topic some time earlier this year at Indiana Univ.