This post is for the theme designers amongst us - it's always good to build up a "tool kit" of resources that you can use when mocking up your themes and creating the theme demos as good content in your theme demo will really help sell your WordPress theme.
You have to be a little careful about licensing issues when distributing themes, especially if they are for release on the WordPress directory as any images you use must be GPL compliant. If you choose to use Creative Commons licensed images, they must be under the universal CC0 version. Just recently Flickr announced the ability to choose public domain images in their advanced search results so that is a good starting point, we have listed more sites below that provide photos free for use which are compatible with the GPL.
I have also listed a number of tools and apps which will help you when designing the theme and also some tools which will help you when coding your theme.
Make sure you Bookmark this post and share it with others and enjoy making your design projects a little easier!
Free Stock Photo Sources
Created by a friend of mine Tom Eversley, ISORepublic features his own photography which you are free to use in your WordPress themes.
Unsplash has some great photos with one released each day under the creative commons zero license.
Pixabay is an image search engine of public domain photos.
Some great photos free for personal or commercial use.
Free high-resolution pictures you can use on your personal and commercial projects.
Public Domain Archive
Vintage and modern photography, 100% free to use for your creative projects.
Generate grids of user photos and avatars, customize the sizes, spacing and border radius.
Generate fake names to use in your mockups - perfect for testimonials, staff members etc.
A free photoshop extension to tidy up your messy .PSDs!
A handy tool for creating your favicons, Windows 8 Tiles, Apple Touch icons, Android and iOS icons.
Generate simple loading spinners with animated CSS
Flat UI Colors
A collection of UI colors - just click a color to copy the hex value to your clipboard.
Random User Generator
A free API to generate random users with photo and other details.
Unicode Character Table
A collection of Unicode characters with their HTML code
Paste in your CSS code and this app will format it nicely for you.
Quickly search for the fontawesome icon you need.
A CSS3 generator.
A tool to work out em sizes from px