Before creating a digital presence, it is important to consider whether it is a worthwhile investment of time and money, which is not the case for all businesses. The article "Does Your Small Business REALLY Need a Website?" mentions an example of a restaurant that already has more customers than it can handle. According to the article Why You Need a Website, it's probably better to have no website than one that looks unprofessional. It's almost certainly better to have no Facebook page than one where you insult potential customers.
Assuming the above issues aren't in play, let's talk about some of the different types of digital presence, according to the course wiki, that the bar can have.
Most small businesses start their digital presence with a brochure site, which contains an overview of what the business does, along with basic contact information. A brochure site can be set up easily with existing templates available online, such as through WordPress, making it a good choice if the owner wants to minimize the effort put into a digital presence.
The next step up is an informational site. In the case of the bar, this could be used to promote drink specials or live performances. It's worth noting that this can be done outside the official website, such as on Facebook or Twitter.
The bar might also want to add video, such as showing a clip of a band performing at the bar or just showing what a good time people have there. Again, this doesn't have to be done on the official website, especially if bandwidth is a concern. The videos can be uploaded to a site like YouTube or Vimeo, and the website can have a link to the the bar's channel.
Many business have a data gathering component where they collect information from users in exchange for something. One way the bar could do this is to ask people to sign up for their email newsletter to be entered into a drawing for a prize, such as free tickets to see a band that's playing at the bar. Then of course, the email newsletter could be used to promote other events and products at the bar.
It can be helpful for businesses to have an interactive component to their digital presence. Something with a large user base might be well served with a chat room or discussion forums, but in the case of the bar, it would probably be enough to interact via Twitter or Facebook.
Eventually the bar might want to offer eCommerce on its site, selling t-shirts, coffee mugs, etc. One way to streamline this potentially labor-intensive process is to schedule pickups from the US Postal Service.
There are also other promotional tools available, especially for mobile devices. Many people have apps on their phones that use GPS to alert them when they're near a particular store, and the bar could use this to promote events and products at the bar.