You may already have a good few of the basic modeling tools:
Model Ship Building Tools - A list of tools most commonly used in model ship building
Beside the basic hand tools, you may become interested in something more expensive.
Before you spend lots of money have a look at some altrnatives.
Custom Scroll Saw - Using a bit of ingenuity and some spare parts on hand Jerry Glickstein was able to build this scroll saw. (A major project in its self!)
Thickness-Sander Project - An outline of how Bob Weiss, fellow modeler built his own thickness-sander for his workshop. May give you just the inspiration you need to build your own.