[R] multiple comparisons with non homogeneus variances

[G. Allegri]

This is a mixed question, between theory and practice.
I have a dataset with a continous variable grouped by a 33 levels
factor. After having log-tranformed my original data I can assume the
normality of my data but I have two strong departures from the basic
assumptions for anova and t tests: *unbalanced data* (some groups
contain ten samples, others hundreds) and *non homogenity of
variances* (tested with a kruscal test just for a qualitative
assessment).
Is it possible, and how, to make multiple comparisons when these
conditions are met? In past anaylises I've simply used the
pairwise.t.test function to do multiple t-test, but know I have to
consider the above situation...

Thanks a lot,
giovanni