This page basically contains all the files I have concerning U61. Some files are available on various mirrors, in case one of them has really poor bandwidth or if it simply goes down. Mirror list and file locations are likely to change, however this page ( http://www.ufoot.org/u61/download ) should remain stable.
It also possible to get the latest work in progress , but carefull, this might simply not compile and/or not work at all. In doubt, prefer the "offical" versions listed on this page.