I was looking for a simple freeware for generating UMLs and class diagrams spesifclly.

Here is some of the better ones I have found:

ArgoUML

open source UML modeling tool.

StarUml

Another cool open source UML modeling tool.

hierarchy

A freeware by white magic software.

AmaterasUML

AmaterasUML is an Eclipse plug-in for drawing UML class-diagram, and UML sequence-diagram.

ObjectAid

The ObjectAid UML Explorer is a UML plugin for Eclipse. It provides a graphical view on your Java source code.

Umlet

UMLet is an open-source UML tool with a simple user interface

fujaba

NetBeans

Of course NetBeans itself comes with a very good UML tool built in.