If you search the entire web, you can find thousands of different kind of resolutions for images.
Below are the most popular image resolutions I have listed.
With respect to size: 1 -Small -less than height=200 and width=200 ( Ex: 150*100, 165*132, 160*160) 2 -Medium -less than height=400 and width=400 ( Ex: 300*300, 350*250, 330*226) 3 -Large -all other sizes considered as large With respect to aspect ratio: 1 -Wide -Aspect ratio like 16:9 2 -Tall -Most latest mobiles uses Tall Aspect ratio 3 -Dual -Used where extended monitor is added for your laptop or PC With respect to pixels: 1 -240*320 - For Mobile backgrounds 2 -320*480 - For IPhone Backgrounds 3 -480*272 - For PSP backgrounds 4 -640*480 - For few mobile phone backgrounds 5 -800*600 - Mostly for desktop backgrounds 6 -1024*768 - For wide desktop backgrounds 7 -1152*864- For Desktop 8 -1280*960- For desktop and posters 9 -1280*1024 - For desktop and posters 10 -1800*1440 - For desktop and posters 11 -1920*1200 - For desktop and poster 12 -1600*600 - For desktop and posters 13 -2560*1024 - For dual screen Even though there are many websites where you can search the images through out he web there are only few which provides good filtration with respect to resolution, Ex: Image Search Engine