● Consolidating wallets between different computers. A quick firstbits lookup will show the full address to send Bitcoins to, rather than having to email a full Bitcoin address to myself or attempting to manually copy it down.
● Relative needs to pay me back for dinner? A friend bought a piece of computer hardware from me? If they need to pay me, I simply tell them what firstbits address to send it to, rather than having to remember to carry a QR code with me or emailing them a full Bitcoin address.
● Shortening the address for space-sensitive online postings, such as forum signatures, forum avatar text, email signatures, or tweets.
● Tipping! In the future, artists might sign their artwork with their firstbits addresses, in an effort to gain tips for as long as the image circulates. Writing in a full Bitcoin address wouldn't be practical, and relying on a centralized address shortener wouldn't ensure longevity of their tips.
● Memorizing the Bitcoin addresses of other people. For example, I might know that my own firstbits address is 1justin, which can prove handy, but because they are so short, I might also remember a friend's firstbits address is 1jones, and a relative's firstbits address is 1jerry. In this way, I can pay them for any reason at any time without having to ask them for an address first.
I could go thru many of these points and argue, saying there are other ways to solve these issues. But if you want to really kill off first bits, create an alt coin like namecoin that all they do is store shortener ID and the bitcoin address it points to. First bits is at the basic an encourage of spam and we can't have that right now.
I'm sorry, I completely disagree. Firstbits do not create spam any more than any other transaction creates spam. They solve real problems in a simple and better way than any other address shortener ever has.