Neembuu Uploader is a batch uploader that allows you to easily upload multiple files (simultaneously) to 6 file sharing hosts: easy-share.com, filedropper.com, filedude.com, hotfile.com, ifile.it and uploadmb.com.
Glippy is a clipboard manager for the Gnome desktop. Some of its main features are: Ubuntu appindicator support, it can store test from both keyboard and mouse (select some text using your mouse and it will be available in Glippy), you can easily access the keboard using a hotkey (CTRL + SUPER + C by default, but it can be customized).
simple Nautilus Actions script to upload images to Imgur.com via right click.
If you want to upload a lot of documents to Google Docs, it's difficult to upload them one by one. You can send the documents by email, but this option is not very reliable and not all the formats are supported.
Publishr is a quite useful GIMP plugin. With Publishr, you can directly upload images to Flickr and Picasaweb from GIMP. The latest version of Publishr is 0.2. You can download it at here.