Is there any useful software for filling out pdf-forms other than Adobe Reader?

Evince Document Viewer (Installed by Default)

Here is a screenshot of an editable PDF file being filled in my desktop for you to see Evince Document Viewer in action.

Like this, there should be some other good PDF readers that will allow you to perform this task, but this is working for me and it is really lightweight.

Good luck!

Xournal

It is not a reader, but a tool to annotate PDFs and other files. It will not execute the form (so no auto-calculation or similar stuff), but it will let you fill (by hand, using a text tool, selecting a font, etc) and print it.

Not the best tool for normal use but really handy sometimes.