This list could be much bigger than it is now,given the increasing number of retailers which are beginning to accept BTC as a means of payment.I'll write some of them now,but with time I will probably also remember some others.

SteadyTurtle -Buy Hosting&Domain -I use them for years,great service.

CoinPayments -Payment Gateway -Use them many time for different service.

Apmex -Buy Gold/Silver/Platinum -Never try,but I think they have good reputation.

Alza -Buy electronic/mobile phones/health&beauty and a lot more (EU based)