Stolen gratuitously from here
"To allow users to create a personal web-accessible directory called "public_html" in their home directories, you will need to uncomment the following lines in Apache's http.conf:
AllowOverride FileInfo AuthConfig Limit
Options MultiViews Indexes SymLinksIfOwnerMatch IncludesNoExec
<Limit GET POST OPTIONS PROPFIND>
Allow from all
<LimitExcept GET POST OPTIONS PROPFIND>
Deny from all
(You will need to modify the first line if users' home directories are not in /home.)"
As a side-note, when I installed Apache with apt-get, this feature was enabled by default (or, I think dpkg asked me if I wanted it and Yes was the default). YMMV.