Memory is an extremely light-weight utility to help you monitor your RAM usage. It runs in the status bar and displays currently available "Free" RAM. Click it to show a breakdown of how your RAM is being used:
Green - Free RAM
Blue - Inactive RAM
Yellow - Active RAM
Red - Wired RAM
It can display both absolute values in GB and percentages of total memory available. Configurable in settings.
With Family Sharing set up, up to six family members can use this app.