In flickr, I you can upload full res, and view it full size. It is one of the settings in the account. Personally, I set it to limit the size of the image people can see when viewing, and that is only to limit picture thieves from getting a full res image (I have had my pictures show up on an advertising / articles). If you want people to have access to the original file to show it full res, you can change the settings as follows:

Under Your Account Settings, go to the tab: Privacy & Permissions

Click edit on the "Who can access your original image files?" line, and you will get to the following page:

Access to your original image files and other sizes

This setting applies to your whole photostream, except items you've licensed with Creative Commons(because doing that means you're okay with people using them).
Please note: Some cameras including camera phones include information about your camera settings, camera type, location and other information in the original file. If you don't want this to be available to people you should restrict who can download your originals.
This setting lets you choose who can see your original image files.
Enabling this setting also places deterrents to discourage downloading of your other sizes. (And we really do mean "discourage". Please understand that if a photo can be viewed in a web browser, it can be downloaded.)
Who should be able to access your original image files and other sizes without deterrents?

_ Only you
_ Your friends and family
_ People you follow
_ Any Flickr member
_ Anyone (Recommended)