Social networks are a good way to show off your products and promote your events. A couple of quick thoughts: On the promotions side my theory is that only 50 percent of the people who say they will attend will actually do so, though you'll usually end up having more than say they will attend due to people inviting their friends and people at other events wanting to skip around.
On the Equipment side it's good for business. Not many people just show up to the store and pick up a mixer there's a lot of research that goes into it and if you keep showing your upcoming products as they develop people keep you in mind when they are ready to purchase. Whether it's a quality product or not people usually look a the newest, shiniest items first.
On the install side, well who doesn't like pics of installs?
Rane 2016S, CDJ-200s, Traktor Scratch Pro, Sony MDR-7506, Fostex PM 0.5 monitors.