PhotoRack
Photo Rack has a huge collection of over 27,000 images, nicely categorized. The categories are broken down into subcategories, but there is no search function. This is a place to browse, seeking that perfect image. No registration required. No ability to upload, but downloading is a breeze.


Stock.XCHNG
Stock.XCHNG is my favorite site for free stock photography. Searching and browsing is a breeze, and they even include a lightbox, which is a handy way to save images for later use.


Everystockphoto
This is a huge resource, currently indexing over 3 million photos! Every Stock is a search engine for free photos, and it searches many of the sites listed here. Search options allow you to specify
license type. Highly recommended.


Imagebase
The photos on Imagebase are free to use, and are licensed under a Creative Commons license. Images are available in two high resolution (1600 x 1200 or 3072×2048) formats.


Morguefile
Morguefile is a completely free source for stock photos. Check the FAQ for usage. The term “morgue file” is used by illustrators and others for a stockpile of images used for reference material. Nothing ghoulish about it!


Openphoto
Openphoto groups their completely free photos by categories, and offers a search function as well. Registration is only necessary if you’d like to upload photos.


Stockvault
Stockvault is a very classy, modern site with thousands of images and some Photoshop tutorials. Membership is free and unlocks some additional features, such as a lightbox. Definitely worth a look.


Unprofound
Unprofound is unusual in that photos are grouped by color, rather than category. There is also a search function. Registration is not necessary, but allows you to create a free online portfolio, and to contribute to the ever-growing collection.


FreePixels
Freepixels has corporate-type images usually only found on pay-per-image sites. It has a search function, categories, and a tag cloud, so finding an image is easy. There are also some good abstract backgrounds here.

FreeFoto
Freefoto is made up of 117600 images with 153 sections organized into 3285 categories. There’s a search function, and usage is unrestricted. Just include an attribution link back to Freefoto.