For the analysis of the diversity microsatellite markers remain interesting markers, but all depends on the species. For some who genomic characterization is developped, a caracterization by the microsatellite is no longer interesting. For others such as moineux used microsatellites is interesting. For detection gene a famillial study it's nececer and screning genome with some microsatellites one every 20 CM;
For Identification of a gene and diversity analysis in eukaryotes like nematodes kindly refer to the work done using Internal Transcribed spacer regions.
you could perform a search for SSR - either in genomes if available, or in ESTs collection. and than ... just try on your materials. If you find many sequences, they can be useful and work for your purposes.And, by the way, a thorough search of the literature could give you an hand.