I've developed a solution for a few of my databases which may work for you (depending on what exactly you are trying to do).
Two things are needed: a way to distinguish between new records and old ones. I have used a check box. You also need a form that will be open at all times.
Create a query that counts the number of new entries. Display that number on your form. In the timer event (you can decide how often you want it to check), Requery the value and then write an if statement to display a message if the number of new entries is greater than 0.
I have utilized this in a messages DB that checks every 5 minutes for new messages. It works well. I have also allowed functionality for users to turn off the alert system and I believe when I get a chance I am going to build in a way for the user to change how often it will check (some are finding 5 minutes too often).