NameVirtualHost ip1.ip1.ip1.ip1
NameVirtualHost ip2.ip2.ip2.ip2
<Virtualhost ip1.ip1.ip1.ip1>
ServerName site.com
ServerAlias
www.site.com
DocumentRoot /home/user/domain.com
</VirtualHost>
<Virtualhost ip2.ip2.ip2.ip2>
ServerName site2.com
ServerAlias
www.site2.com
DocumentRoot /home/user/domain2.com
</VirtualHost>
Technically the namevirtualhost stuff on top is only if you're going to host more than 1 virtual host / IP and in this case you're not but its there just to be safe.