You can create articles with content trending and interesting (Google Trends is your friend) and submit it to:
* Reddit
* Hacker News (only about technology)
* If you are offering a web service you can post in Pineapple.io
* Promoteproject.com
* Important forums (like this or ukbusinessforums.co.uk)
* Try to promote it on new social networks and web services
* Offline ads sometimes can be useful (posting an advertisement in a bus stop, for example).