The twitter tool tweetake is an excellent and really helpful mashup for the twitter members who want to keep a backup of the complete twitter information which includes -

Twitter Followers
Twitter Friends
Twitter Favorites
All your twitter updates

Or backup of just everything.
When you think why this tool and how it helps, this is what tweetake developers have to say -

• Twitter may lose followers again like it did in June / July
• You may change your Twitter name and want to re-follow the people you were following, and contact the people who were following you
• You may want to refer to an older Tweet – currently Twitter does not keep all of your older Tweets
• You may just like backing things up, ‘just in case’, like us.

It has happened earlier, Shoemoney lost all his information in twitter and had to lose all his followers and people whom he followed. That hurts as he had thousands of followers and followed hundreds of them. So, better backup if you have a considerably large number of followers and huge number of updates.
I just backed up mine and took less than a minute. You would get a file to download.

Note – When you are using this tool, shut down any twitter client, as this program is not affiliated to twitter and so it is not allowed to backup if the client is not allowing it to do so.