A beautiful movie about Moebius transformations is
on youtube:
video
More information and a link to a high resolution version on
Info
A webpage containing mathematical challenges for
various levels (for children between 5y and matura...):
nrich
The nrich webpage presents mathematical problems. It is updated
monthly. (Stages 1,2,3,4,5 refer to the UK school system - if
you look through the problems you will certainly find
your way around).