The first 20 from the Euler Project:
http://www.newlisp.org/syntax.cgi?euler.txt
Thanks to Sponsy for drawing attention to this here:
https://github.com/sponsy/project-euler-newlisp
I also found the following two sites inspiring, because they discuss the mathematical background of the problems, and sometimes compare different programming languages.
http://www.mathblog.dk/category/solutions/project-euler/
http://code.jasonbhill.com/project-euler/
Many of the solutions on the newLISP page are from those three sites. Most of the problems are heavy on number-crunching and don't really show newLISP specific capabilities, but still it was fun.