A question that comes up frequently is how to make name-based virtual hosts work with SSL. The answer is that you currently cannot. Name-based virtual hosts depend on the Host header of the HTTP request, but the certificate verification happens when the SSL connection is being established and no HTTP request can be sent. There is a protocol for upgrading an existing HTTP connection to TLS, but it is mostly unsupported by current browsers (see RFC 2817, at http://www.rfc-editor.org/rfc/rfc2817.txt).
Can I use SSL with other protocols?
The mod_ssl module implements the SSL protocol as a filter. Other protocols using the same Apache server can easily take advantage of the SSL.