p-hold

It's another placeholder service.

Only this one is more configurable and returns the most
interesting CC-licenced images on Flickr.

Default - /w/h or /w

Set the image src attribute to p-hold.com/400/300 to render a non-ugly image at the given dimensions.

Keyword - /q/w/h

Set the image src attribute to p-hold.com/kitten/w/h to render an image of a kitten at the given dimensions.

User - /u/n/w/h or /u/n/w

Set the image src attribute to p-hold.com/u/name/w/h to render a random image from the given user at the given dimensions.

Filter - /w/h/f or /q/w/h/f

Append a hex code, 'gray' or 'blur' to the end of the source URL for a colorized, grayscale or gaussian-blurred image.

Advertising - /x

Set the image src attribute to p-hold.com/x where x is the ad unit abbreviation.

Valid ad unit abbreviations

/MREC - medium rectangle - 300x250
/LREC - large rectangle - 336x280
/LB - leaderboard - 728x90
/LLB - large leaderboard - 970x90
/SKY - skyscraper - 120x600
/WSKY - wide skyscraper - 160x600
/LSKY - large skyscraper - 300x600
/S - square - 250x250
/SS - small square - 200x200
/B - banner - 468x60
/HB - half banner - 234x60
/VB - vertical banner - 120x240
/BTN - button - 125x125

Note: including a keyword in the image URL will be slower than the other methods as it involves realtime polling of the Flickr API. Querying for a given size (with or without a filter) uses local copies of images, removing the extra request overhead. But keywords means kittens, so it's a worthwhile tradeoff. Username request do not guarantee CC licensing, but return public photos only.