On today's portable Macs, especially those packing SSDs, storage space can be somewhat limited. It can be pretty easy to fill up all available space with a few large downloads, rendering your computer starved of space and creaking under the strain. Problem is, unless you watch your HDD space like a hawk, there aren't many visual cues as to when you're running low on space, and that's what Disk Alarm aims to put right.
Disk Alarm does one thing; it checks the amount of free space you have on your main drive and alerts you when you get below a user-definable threshold. It's nice and simple -- you adjust one slider to set the threshold and one to set the check interval.
You can get Disk Alarm to play an audible alert along with a warning when your disk gets low, but it'll also show how much free space you have in your menu bar for at-a-glance reassurance. The application used to be able to hide up into the menu bar when you closed the settings window, but as of a recent update, Apple blocked the version that had that ability. Hopefully the developer can find some way around Apple's odd blockade, but in the meantime, Cmd+W will close just the window and leave the menu bar icon.
Disk Alarm is available for US$3.99 from the Mac App Store, and should save you time and heartache the next time you run out of space. If you've got any good experiences or favorite alternatives to Disk Alarm, sound off in the comments.