I was in JJB Sports today and they are giving away £40 vouchers with every purchse. I used a £10 shoe voucher to get a pair of Asics Kayano 17's for £69.00. Vouchers valid until November.
Edit: I have just looked in the voucher book and the codes below can be used online.
£10 off over £50 spend - 40vouch10
10% off next purchase - 40vouch8
£5 off over £25 spend = 40vouch7