For many of us, flickr and picasa are just way too 'light' for our blogging needs. Imageshack with its unlimited storage and registration-less service is an easy winner for bulk image uploads especially for people who like to link to images and hate those stupid alert messages about depleting storage etc.
Imageshack has recently upgraded its interface. And they now have a plethora of uploading options for its users, much like flickr. It has introduced the ImageShack Uploader (remember flickr uploadr?) for its users. And Linux lovers need not fret coz there's now a Linux version of their uploader! Although I wasnt able to download the .deb file, I'm pretty sure its a temporary issue and will be resolved soon.
In the meantime do check out the awesome uploading options imageshack has managed to come up with. (Imageshack uploading options)