Note that bitcoin is not anonymous by design. There is a certain level of privacy, but all the transactions are publicly logged.

Bitcoins are aimed at everyone. To find out the motivation of the current userbase you would have to survey all users But yes, currently there are mostly tech geeks, libertarians and some drugs fans (money laundry isn't very popular in my opinion).

I think bitcoins would simplify online payments and transactions. For example, I live in europe, but I like dealextreme.com because they offer free shipping and they have cheap stuff. It would be cool if they let me pay with bitcoins and avoid the fees from Eur/USD conversion. Other area where bitcoins could be useful is micro-payments.

Your mom probably won't use bitcoins anytime soon (or ever). If bitcoins take off, they will take their place as an alternative way to pay online. So if bitcoin succeeds and if your mom shops online, she might use bitcoins in a few years.