I have my own domain for important images, for anything else I use temporary solutions such as www.imageshack.us
because its often quicker to upload multiple images and retrieving the image URL's. I use them often for paint overs and help for others if words are not enough to explain things, its not that trivial if those images get lots after 3-4 months.
A own domain and web space is not that expensive and it really is the best place to store your personal stuff. I have been backtracked several times by companies and other persons that saw older stuff from my that of course was linked to my domain and website which is how they often contacted me.