Psst, buddy, wanna save a few gigs of storage? Try deleting some of your old backup Lightroom catalogs.
If you’re like me, you often let LR back up its catalog data when it prompts you to do so (and if you don’t, you should–it’s a pretty painless insurance policy). Unfortunately LR doesn’t automatically delete old copies of the backup data, and I noticed recently that I had several gigabytes of “.lrcat” files hanging around my hard drive. These live in a “Backups” directory adjacent to your Lightroom catalog file (in my case, in Pictures/Lightroom/Backups). I deleted all but the last two or three backups, figuring I couldn’t use that many backup copies (and that the older ones were probably pretty out of sync with the current state of my image collection).
Nice JDI-style bonus: Instead of interrupting you when you just want to get to work, Lightroom 3 now prompts you to back up on quit, not on launch. I was pleased to see that Scott Kelby noticed & digs this change.