Design

• DeviantArt - A community dedicated to all kinds of art, be it digital painting or sculpture. You can submit your own work and comment on the work of others.
• Pixel 2 Life - A site with various tutorials regarding the area of design. Several tips and tricks for Photoshop, Cinema 4D, 3DS Max, etc...
• PNG Factory - A site with lots of high resolution .png icons for your applications, games, etc.

Games

• FPSBanana - A site which provides varied custom content for the most popular games of our times. Be it RPG, FPS or RTS, you're sure to find lots of skins, models, sounds, GUIs to please you.
• Orisinal - Site with many flash games with a great design and, at the same time, great gameplay.

Humour

• Cyanide & Happiness - Daily comic with often stupid humour but nevertheless entertaining :)
• Dark Monkey - Random and cool images to share with friends or use on special occasions
• Family Guy - Site with all the Family Guy episodes (or most of them) available for free and streaming! Great time-killer :D

Programming

• Portugal-a-Programar - The biggest portuguese community of programmers. Here you'll find tutorials, discussions and examples regarding programming in a variety of computer languages. Portuguese only.
• SQL Connection Strings - If you work as a .NET developer and you often deal with databases, this site is essential for you since it provides the various SQL connection strings required to properly connect to a database.

Movies

• LegendasDivX - The biggest portuguese subtitles site with subtitles for hundreds of movies and series.
• Open Subtitles - An international subtitle portal. Get subtitles for thousands of movies in a great variety of languages.
• SubScene - My favourite site for english divx subtitles (thought it also contains subtitles in other languages).

News & Topics of Interest

• Digg - A social networking site where users are able to vote on their favourite stories/news/articles. The top stories show up on the front page!
• Neowin - A site with news regarding the latest IT issues, software updates or game novelties.