Outdated configure advice concerning libssl
If you lack libssl tor's configure fails with...
checking for openssl directory... configure: WARNING: Could not find a linkable openssl. If you have it installed somewhere unusual, you can specify an explicit path using --with-openssl-dir
configure: WARNING: On Debian, you can install openssl using "apt-get install libssl"
configure: WARNING: You will probably need libssl-dev too.
configure: error: Missing libraries; unable to proceed.
This is all fine except the openssl package presently doesn't exist in either ubuntu or debian sid...
http://packages.debian.org/sid/libssl https://launchpad.net/ubuntu/+source/libssl
Installing libssl-dev did the trick for me.