These trees were created using one of the xml files provided with the original BEAST paper by Drummond and Rambaut (2007).
They provide an example of 17 dengue virus serotype 4 sequences from Lanciotti et al. (1997) (available as DengueSeqs) and xml files with varying priors for model and clock rate.
Here we include a random sample of 500 of the trees (from the second half of the posterior) produced using BEAST v1.8 with the standard GTR + Gamma + I substitution model with uncorrelated lognormal-distributed relaxed molecular clock (file 4).
A multiPhylo object containing 500 trees, each with 17 tips
http://bmcevolbiol.biomedcentral.com/articles/10.1186/1471-2148-7-214
Drummond, A. J., and Rambaut, A. (2007) BEAST: Bayesian evolutionary analysis by sampling trees. BMC Evolutionary Biology, 7(1), 214.
Lanciotti, R. S., Gubler, D. J., and Trent, D. W. (1997) Molecular evolution and phylogeny of dengue-4 viruses. Journal of General Virology, 78(9), 2279-2286.