Applied online (via an outsourcing HR firm site), upon arrival on site completed skills test, followed by an interview. Questions: why ING? specifics of investment banking/corporate finance (i.e. functions of the job), background questions. No brain teasers. Pretty standard.
Did not make it to the assessment center - there were 2 positions for total of 1,000+ applicants that year (and Lehman had just collapsed, so I doubt if recruiting even continued).