Yup, just think of the perhaps thousands of pictures that this site would have to provide storage for.
I use Photobucket and it works well. One other solution some can use is, if you have your own web site use a silent page. I just set up a page with no links to the homer page and put pictures on it. If I want anyone to see them I can give them the url and I can also link to it like I have for my avatar.
Asus Commando, QX6700@2.93, 4GB Corsair PC28500 Dom, Tt Armor case, BFG 1KW PSU, BFG 8800GTX OC, 2 Raptors in RAID 0 for OS and Apps & 2 Raptors in SATA for music and graphic files and a WD7500AAKS (.75Tb) for large files, video files and back up, X-Fi, 2 Samsung monitors 245t and 244t's @ 1920 X 1200, Plextor opticals, Aerocool, Zalman, Etc. Vista Ultimate SP-1