Not bad idea however.. Alts are just small part of the Habbo community and it is very specific. Unless you can put a lot development and bring a new unique spin on it e.g. weekly competitions etc. If i was going to create something like this id create a whole system such as
http://www.pixeljoint.com/ obviously aimed at Habbo.
It could work, i just believe fansites have stepped up from the usual generic sites and to be up their with the top sites you have to think heavy development / web 2.0 / Great design / dynamic functions.
If you are going to create something id suggest you do some hard research. I just spent the better part of three months researching and developing test systems for a new up an coming project.
On the other hand if you are going for small an just something to do then you can easily create something within a couple of days, it probs wouldnt create much traffic that way but it would do what you wanted.