I have acted as an assessor in assessment centres and development centres for the past 15 years. The former are for selection purposes, the latter for identifying development needs. Both can use a variety of observed exercises where the candidates are scored against a range of behaviours or competencies.

In addition personality questionnaires and measures of ability may be used. Candidates are given feedback on their performance. In the case of development centres, this feedback forms a major element of the centre and leads onto significant personal development planning for each individual.
I use the 16PF, NEO, MBTI, EQi and ability tests.