I'm always putting my wallet in my (kinda tight --at least not baggy) jeans' front pocket.
I've been thinking about asking my step-mother to sew velcro inside the pocket as to make it harder for pickpockets to get in when I'd be distracted. It would be invisible and certainly not something they'd expect: from the outside it would just look like a normal pant.
Do you think it could work or do you have any other anti-pickpocketing trick?