I did mystery shopping for a while - just as a pocket money thing really, and it worked out ok.
Not vast money, but sometimes beggars cant be choosers.
One set of 'jobs' I did was to go into a certain bank chain and enquire about moving my account to them - you then report back on how they handled it all etc.
The enquiry took about 30 mins, and I was paid £10 per bank. As I live in the south I was able to do quite a few in my local area, and was managing three a day as one stage - so i was happy.
I also visitied McDonalds ! My town has 4 of these, and i seemed to be the only person doing it - so i could end up having breakfast, lunch and dinner there !
I was paid about £5.00 per visit (took minutes anyway) and the cost of the meal, so again, not great money, but a free meal as well so I was happy.
If anyone likes the idea of this, just google mystery shopping - you'll see the companies etc - off the top of my head I think 'gapbuster' or somethng like that was a good one.
All the best
Steve