In Rosenheim, Germany, this past fall, passersby to the local McDonald's would have seen 120 millionaires flipping their own hamburgers. That is, if the event - hosted by Europe's fifth-largest bank, HypoVereinsbank (HVB) - were open to the public.

It was one of 12 experiential events engineered by agency Pleon to promote HVB's new wealth management division, says Claudia Vogt, HVB Wealth Management PR/marketing director.

After UniCredit acquired it in 2005, HVB reorganized and launched the new unit, ultimately charging Pleon with ...