Social Networking buttons in a list of teasers generated using views
Download the ShareThis module. This does what you need.
Here is a quote about it (from the module's project page):

Integration with the ShareThis social bookmarking utility on selected node types.
The code for this project was based on the original share project for Drupal 5.x. The code for this project has been trimmed down to only work with the ShareThis system, and not require any additional modules to work properly.