Loads.
The most revelatory one most friends love is that Now TV has pretty much everything Sky has for a fraction of the price.
Compare your broadband/mobile/energy/insurances every time your contracted period ends (loads of comparison sites these days)
Topcashback is your friend. Route your normal purchases through this website and earn money for nothing. I can pm you a referral link if this interests you. E.g. your new ID contract could have earned you another £20ish if you'd gone through them.
I was one of the original MSE forum members in 2004 - I've been living the "best value for my money" life for many many years.