Despite some Apache comments to the contrary, it is possible to use Apache to host several SSL/TLS hosts on the same IP/port combination. The key is Server Name Indication (SNI), in which the client indicates the host name with which it wants to connect explicitly.

All you really need to use SNI is an up-to-date version of GnuTLS or OpenSSL. Your clients be fine will any major browser written in the last few years.

For details on SNI-support, see the Apache Wiki and the Gentoo wiki.