QoS (prioritize your ssh packets over your netflix stream over your http reqs); ssh server (so that you can have a SOCKS proxy to connect to from public Wifi);

QoS (prioritize your ssh packets over your netflix stream over your http reqs); ssh server (so that you can have a SOCKS proxy to connect to from public Wifi); VPN endpoint; VOIP SIP proxy (to do fancy routing of SIP calls). I'm pretty sure you can install a web browser and serve up static content from a consumer NAS too. Basically, it lets you do a large subset of what you would be able to do with an always-on computer, but without burning all that power.