Pico de Gallo for Chrome is an extension for Google Chrome. It's very lightweight, and focuses on doing one thing well: reading and sending tweets.

Pico de Gallo for Chrome Features:
1. The basics: Direct Message, Reply, & RT right from Pico de Gallo, linkifies URLs, @replies, #hashtags, and even $stockquotes
2. Supports geolocation and also has fancy inline image previews!
3. Mute users (not unfollow them, but just mute them. It's nicer.) by clicking on the user's icon revealing a menu with more options
4. Extends short links (using the same menu)
5. URL shortening (with bit.ly), used for when your tweet is just toooo long to send.
6. When you want to mention ... what's-his-name ... ? while tweeting, if you type @, you'll be guided by Pico de Gallo to remember exactly who you're thinking of!
7. Direct Message inbox checker
8. Desktop notifications for @replies (be sure to check the options page to turn it on; it is off by default)

The license of this software is Freeware, you can free download and free use this browser plug-ins software.