I like to have someone at work that I can buddy with. It works well when it is a co-worker who sits closest to you, but depending on how your office is set up that might not be possible. If it is a planned time off then you can meet with your buddy and give them any instructions or information they will need to handle in your absence and any contact names and numbers. I like to have a contact card with my buddy's general information in it such as log ins and passwords as appropriate.
When the time off is unplanned it is more critical to have this information available with easy access. A friend found this out when her co-worker was called away for a family emergency. She had to set up an away voicemail message and fortunately had kept a script of what her away message usually said, She worked for a doctor so it was important that the proper referral numbers were given.
If you have remote access it is easy to do these things yourself from off site, but sometimes you just can't and it is nice to know you can call your buddy and they can take care of it for you. Last week I was sick and could barely get up to call into the office, so it was nice that my buddy could take care of it.
It is also amazing how much we pick up from our co-workers during the day. You hear something while walking down the hall or are copied on an email and know something about the purpose of a meeting coming up. This inside information comes in handy when you need to pinch hit for them when they are away. Many times I am so thankful I had that quick chat or read that email that I was copied on as that was the exact information I needed when they were away.
Yes, it is always nice to have a work buddy. If you don't have that in your office, why not suggest it to the other assistants? Having a buddy can take some of the stress off and give you assurance that you have someone you can depend on. It can also improve team work and general office dynamics.