Software sandboxes

"Safe" module (ch 23.3 in "Programming Perl, 3rd ed) (sandbox)
Ruby Sandbox module http://code.whytheluckystiff.net/sandbox/
Steel Bank Common Lisp http://www.sbcl.org/
http://www.cl-user.net/asp/root-dir (apparently, Common Lisp has a sandbox, but I couldn't find it...)