Vuescan is AWESOME.
I have this cheap Canon USB flatbed scanner that I bought about a year ago. I use to have a fancier HP scanner that I bought about 8 years ago, but it is SCSI, and I don't really have any computers that do SCSI any more. (It's really annoying that there is no Mac OS X support for the Adaptec 2940 SCSI PCI card that I have, but that's a rant for another day.)
When I got the scanner, I had a hard time getting it working. Mostly this is because (unsurprisingly, I guess) the drivers that came with it were complete garbage. When I got it, the drivers were for the Mac OS version that was already old, and they haven't updated their downloads on their web site.
In any case, I needed to use the scanner the other day, and I realized I had reinstalled my OS since the last time I used it. And whatever hacks I did to get the scanner to work before, I didn't remember. Or maybe they just wouldn't work with Tiger.
After some googling around, I found Vuecan, a third-party scanner software package that claims to support most scanners. I tried the free download, and it worked perfectly. No setup, just copy the app into place, and it works. It's a really nicely usable package too; it strikes the balance well between being a data capture tool, and a useful imaging application.
They have a Linux version also, so I am going to try to revive my old SCSI scanner on my Ubuntu Linux machine.
So, if you're on a Mac, need to scan, Vuescan is well worth the $49. Just toss those junky OEM drivers in the trash.