Gnome-Do is a quicksilver-like application for Linux. By itself, it is only a simple application launcher, and seriously speaking, I find that there is nothing great about it on its own. However, if you make good use of the plugins in the repository, you will discover that there are tons of things that you can do with it. Some of them are really a great time-saver and are able to make your life easier.
So here it is, my recommendation of the 8 most useful plugins for Gnome-Do:

Mystickies is a handy application that allows you to stick notes on the webpages you visit. It’s in particularly usefull for someone who does lots of research and reading online. Notes can be put on any pages or articles and will be visible whenever you visit them again. It’s a cool way to mark important points which let’s you quickly remember important details when you come back. You can think of it as a personal bookmarks with explanatory labels scatered around the web. This application is totally free and curently works only with Firefox browser(firefox profile), however extensions for other browsers (Safari and IE) are in development.