I'm not sure I really understand the reply above so I won't say much about it.
A lot of employers who run large recruitment campaigns for significant professional development schemes (e.g. graduate engineers etc.) use a form of profiling or psychometric testing at some stage in their selection process.
Personally I have found it frequently used early in the process as one of very few options open to employers faced with a huge volume of applications and looking for an objective way of filtering the list to a manageable, comparable and interviewable few.
They usually come in two forms, some sort of personality profile and the assessment of some inate skills/abilities. The former seems very soft, impossible to prepare for or influence and generally figures more weakly (I imagine) in the result
The latter, for pilots, usually comes in the form of testing arithmatic, memory, multitasking and motor skills. Sometimes all at once! These can be prepared for by focusing on the skills you know you're weak on and practicing them.
I bought some books and some computer programs but, whilst they surely helped, I'm not sure how much.
Weather you agree with them or not, they are an evil you'll have to live with if you want into the millitary or onto an integrated course and are ultimately impartial, if a little merciless, beasts.