There are various online services of image upload and sharing, follow a review of main features of the best actually available:
Picasa Web Albums the famous service of Google, available also as desktop application, you need a Google account; 1gb storage. A fully featured system of image upload and management, organize them in albums too; correction tools, creativity tools, add geo location and many more.
Flickr other famous service, you need a Yahoo account. Organize pictures, modify them with various tools, geo location features, create posters, calendars, photo books etc… and many more. With free account you can upload 2 videos and 100Mb of pictures each month.
Imageshack one of the most used service for “fast hosting”. Doesn’t need registration, if you make a free account there are more features (eg. collection of own uploaded images), you can also register to the premium service. Direct link sharing on web sites, blogs, forums etc…, you can upload from file, url, webcam, widget desktop, toolbar, plugin, mobile etc… share on social networks sites, resize, it has also a built in image search engine. Max file size 1.5mb, bandwidth 100mb per hour.
Tinypic registration isn’t required and it’s free. Upload images and videos from file or url, unlimited storage and bandwidth, no restrictions on file formats and on file size.
Photobucket requires free registration, upload from file, URL, email or mobile, the free account allows max file size 1mb and max resolution 1024×768, 10GB monthly bandwidth and 1GB max storage.
Organize images in albums, share them, host videos too.
Imgur doesn’t require registration, simple and fast upload and sharing, direct link to images, short url, max file size upload 2mb (with a donation you can increase limit to 3mb).