Although I don't recommend lettering in Photoshop, I don't think there will be many people reading this who don't have a copy installed on their computer, whether they use it for colouring, art clean-up, photo-retouching… as a user since v1.0 (yes, I am that old) I've watched Photoshop grow into a powerhouse and -- for many -- a one-stop solution for digital art and design.
And yet, after twelve versions, you can still experience this scenario: you're working on a Photoshop document, and you go into the 'zone' -- you know the one, where each stylus stroke or keyboard shortcut or mouse click seems to naturally follow the last.
And then… lock-up. On the Mac, this is usually accompanied by the Beachball of Doom and is the point at which you look up at the clock and think -- "Oh, crap, when did I last save this?"
Whatever the answer to this question, it is usually "Not recently enough" as you are presented with the bland, innocent-looking dialogue box that informs you "Photoshop has unexpectedly quit."
Twelve versions -- bearing in mind that Photoshop fills your hard drive with massive temporary files recording in meticulous detail the history of your document -- and yet when you re-open, it can't recall a single pixel that you laid down since you last hit save (which turns out to have been an hour ago). I'm sure I'm not the only person who's had to get up and walk away from their desk in order to avoid visiting harm on their monitor in sheer frustration at this point.
Well, say hello to PSD Autosaver! A functional little plug-in that allows you to specify location, frequency and number of automatic back-ups Photoshop will make while you work. Be aware that (unlike the auto-backup in, say, Quark) it doesn't work while the application is idle, so if you work for less than the back-up interval (say five minutes) and then switch to another application, your work will not get backed up until you go back and work for another full five minutes.
(Edited to add: It's worth mentioning that this plug-in saves one or more back-up copies of the document, but doesn't overwrite the original that you are working in.)
Although I can see that being a little annoying for some people's workflow, it's still immeasurably better than the current situation. The free trial download linked above only works for 30 days, but $19 for the full license looks like an absolute bargain to me.
(Note: no, I'm not on commission! I have, however, lost enough work to the sort of scenario I describe above to think an autosaver is a complete god-send!)