Now, Just You Back Up There A Moment, Young Fella...

With a big project like The Great Game just completed, a young man's fancy turns to backup strategies. At 7.5 gigs a pop, I don't want to keep more than one episode of The Great Game on my Mac's 60 gig hard drive at any one time; I leave low-resolution copies of the pages for reference, and the rest get shunted off onto a variety of external disks.

I have a short-term and a long-term strategy; day-to-day (in fact, any time I get up from my desk for more than a couple of minutes) I back up onto 60 gig Smartdisk Firelite firewire hard disks; I have one dedicated to each of my two Macs. They contain backups of my current projects, software, resources like fonts, plus a bootable copy of each Mac’s system folder made with the handy freeware app Carbon Copy Cloner. I can boot from the external disks to repair the Mac's own hard disk; at a pinch I could even use them to keep going in the face of a total hard drive failure.
My long-term strategy is twofold; backups onto CDs or DVDs and onto larger (320 & 500 gig) mains-powered Formac hard drives. The CDs and DVDs have the advantage of simplicity; there's little to go wrong with them mechanically and files written on them can't become infected by viruses. The hard disks are more convenient to back up to and are intended for long-term future-proofing; when CDs or DVDs start becoming obsolete it would be a pain to transfer the contents of hundreds of backup disks to some new medium; in comparison, it should hopefully be quite easy to dump the contents of one or two big hard disks onto whatever the brave new format is.

Software-wise I rely on three apps; two backup programs and a CD burning app.
Intego's Personal Backup X is my favourite backup program for day-to-day use as it will simply copy the contents of one named folder into another without compressing the backed-up files into some weird format. This means I can just access the backed-up files from whatever disc they're on without having to go through a restoration procedure first. Personal Backup X is Mac-only, simple to set up and use, and fairly cheap (£50-ish). It won't back up directly to CD/DVD, but you can back up to a disk image and then burn it afterwards.
Apple's own Backup software does save files to a compressed archive, but it has automatic pre-sets that let you easily back up normally awkward-to-get-at stuff like mail messages and application preferences. Useful for backups against that nightmare computer failure. Mac-only (requires a .Mac account), will save to CD/DVD*, FireWire hard disk, and iDisk.
Until recently, the only CD-writing option for Mac users (apart from the slightly limited option of the Finder) was Roxio Toast. However, while trying to find out if you could write multi-session DVDs, I stumbled on an application called NTI Dragon Burn, which I now use all the time. Originally a PC application, Dragon Burn isn't guaranteed to work on all Macs; it's notorious for breaking down when users upgrade their system software, though NTI are apparently pretty good at issuing free upgrades to get the show back on the road. My copy has worked fine with Mac OS 10.2.8-10.3.9, though I would recommend downloading the free trial version to check it works with your machine before buying.
What sold me on Dragon Burn was the number of useful extra features that Toast can't match. Once Roxio perfected disc-burning in the background under OS X (Toast 5), they seemed to run out of ideas and concentrated on turning Toast into an all-singing media conversion package ("Turn your nuisance viagra spam emails into a professional-quality Quicktime slideshow on DVD using drag-and-drop alone!"). NTI, on the other hand, kept adding simple-but-useful extra features, like simultaneous burning to multiple recorders, disc spanning (writing large chunks of data to more than one disc) and multiple sessions on DVD (though only DVD +RW, so you'll need an external burner). Unlike the spreading octopus of Toast 6, Dragon Burn is small and cheap ($20 for download version).

Finally, if you did want something to replace Toast's sound-recording facilities, I thoroughly recommend a little app called Audio Hijack Pro by the wonderfully-named Rogue Amoeba. This will let you record sound from any source coming into the Mac, or any program that plays sound - so you could digitize your old LPs by running a line from your stereo to your Mac's sound-in port, or (as I do) record digital radio programmes from the Internet or even theme music from DVDs. The unscrupulous might even choose to re-record tracks downloaded from iTunes to MP3 format. allowing them to be used in a wider variety of players (not that I could ever recommend such a thing).
Audio Hijack will record directly to AIFF, MP3 and AAC in a variety of quality settings. It has a large number of filters, most of which I don't know how to use (though I do use "Double Gain" for boosting the volume of DVDs played through my older Mac). It also usefully stops recording when a stream cuts off, so I can leave it recording a half hour programme, safe in the knowledge that if I forget it for three hours I won't come back to find my hard disk filled with a vast MP3 file, most of which is the sound of silence.

*Like most Apple software, it normally only works with the Mac's built-in CD or DVD drive, though my LaCie DVD writer came with a software plug-in that makes it compatible.