Here is a guestbook. Unfortunately, it's in Polish, so it will be like that until I'll find a new host.
To use it, click the bottom text on that grey area.
If you clicked it, just type in your name on Imię and some random email on Email.
On this 'Numer GG' type some random numbers.
Then just tick the box on this 'Nie jestem robotem' and click this 'Dodaj' button.