Standard issue standards hunter
I've been drooling over DVD writers for quite some time now, mainly due to the fact that my music making hobby renders me with large datasets which I would be wise to back up. I've done so with CD's, but the last time I backed up my sample collection I needed 11 disks to do so! Ouch.
So far I've kept away from writable DVDs for two reasons: Price and standard/compatibility issues. The thing is that there is a plenthora of formats in which DVDs can be written: DVD-RAM, DVD-R and DVD-RW, DVD+R and DVD+RW. Naturally their not cross-comatible (yet).
I did some research on the history and existing standards of DVD writing, and found this nice DVD format introduction. I also found a very comprehensive FAQ on DVD in general, here is a link to the section dealing with recordable formats. I'd recommend both for anyone who's planning to buy a DVD writer. A little knowledge might save you quite a bit of headache.
Finally, for my Finnish readership: The MBnet Hintaseuranta page for DVD writers.