Recommended by one of our site users:
"They print on Fuji paper, and the quality is really good."

FOTO.com is an online photo printing service that delivers your printed pictures to your doorstep.

In addition to photo printing they offer also photo books, posters, photos on canvas, alu or plexiglass as well as personalized gifts such as mugs, mousepads and t-shirts.

Create & order photo books, prints, cards, canvas & more

Park Cameras offer photo printing services.
In addition to just prints from digital files, they also offer: 35mm / APS Film Developing, Prints from 35mm / APS Film, Prints from Mobile Phones, Prints from Slide and more.

Photobox are one of the leading online photo printing services. Apart from prints they also offer Photo Books, Personalised Cases, Cards, Wall Decor, Mugs, T-shirts, and more. The are fairly cheap and normally very quick.

25 photo prints for free!
Pixum offer prints, photobooks, canvases, calendars, cards and various gifts.

Snapfish is a leading online digital photo service offering free sharing and storage of your digital photos with prints at just 9p.