CocoPPa Keyboard - an iOS 8 keyboard customization app - may look like it is designed for children at first, but it allows you to create some beautiful backgrounds.

You can chose an existing background (I love the mustaches) or design your own by tweaking the colors, design, letter size, spacing, and more - although do be warned as the backgrounds can obscure the keys. The keyboard is smooth and fast, with impressive next word prediction.

Overall, CocoPPa Keyboard adds flair to your phone.