Another great way to use them is to provide both passive readers advisory for patrons who wish to explore your digital collection on their own as well as to support paraprofessionals when they are called upon to provide readers advisory on the phone, in virtual chat, or while on a public service desk. Even if a patron wishes to read a physical book or listen to a CD audiobook, having an easily accessible digital collection/list/shelf available will give your staff a place to start. They will be able to see authors, series, and subject headings that can give them some direction.
Readers Advisory specialists can ask front line staff what kind of RA questions they are receiving and what sort of books patrons are discussing with them. You can also use read alikes for best sellers and read alikes for movies and TV shows that are popular in your area. Check your circulation stats and look for genres, subgenres, and non-fiction areas that are moving in your building. If you are part of a system with more than one branch, don't forget to look at more than one location.
Programming is another area that you should not ignore. Tie in your digital book and audiobook collection to your programming. Patrons who enjoy a virtual or in-person program can explore topics further, starting with the list you provide. These patrons will have a better readers advisory experience if there is a list of titles that can be built upon.
If a genre that you are not familiar with is something that staff and/or statistics indicate that you should focus on, ask the people that your in your library system. There are people all over your system who are fans of genres, subjects, and part of fandoms that you are not well versed in. Have that person who loves military science fiction create a list for you. Ask that gothic horror fan to look at your eBooks/eAudiobooks and see what they would add to a shelf. Maybe a short story fan lurks in your facilities department and would love a change of pace and a chance to promote their favorites.
Having tools like online displays available will ultimately serve your patrons better as they can find more of what they love while also receiving better service from your staff. We can't all be experts on everything and it's a good practice to give staff a place to start when a patron asks.