If you are looking for a Twitter client that is minimalistic and extremely lightweight, then Ada suits the bill.
To get started, go here and hit the “Install Now” button to install Adobe Air :
Click yes and follow the on-screen instructions to complete the installation. Once installed, all that shows up is a tiny window asking for Twitter login, enter credentials as usual :
The tiny window is all that is for this Twitter client, you can see all the various tweets listed. To post a tweet, click the balloon icon and start tweeting.
Access various options by clicking the inverted triangle :
Overall Ada is pretty simple to use as well and minimalistic without any clutter.