Twitter is not only for the Commercial use... The twitter personal account is highly need over internet to make you a perfect web user...
There are some reasons for it...
If you are user of any social networking sites like Facebook, Orkut, Hi5 and others, then your friends want to know more about you... So, Twitter is the fastest and the easiest way to share your daily status. You can send your status in the form of small message to them who are listening you.
You can check your own fans by increasing the amount of twitter followers. The follower are very much important for every twitter user..
The personal twitter user also works as the Open identity for you, with which you are able to access to any of the site you want to participate. Even i am having many twitter accounts for my different products or blogs, then even i created a personal twitter account. My Twitter profile is : Arijitblog. Here My name starts with "A" which i feel really interesting...
This twitter profile will help me to identify me as the blogger all over the internet and i am going to put my profile link everywhere i participate...