I'd been wondering this myself as I'm getting an SSD for my new MythTV frontend: the advice in the post above is about where I'd got to. Another possibility is to put the Firefox cache onto a RAM disk so that it isn't continually writing small files, or to increase the RAM cache size and disable disk caching completely if that's possible.

You may also want to increase the commit time so that files don't get written out to disk every few seconds; I know that's a mount option on ext3, I don't know whether ext4 supports it or uses its own heuristics for deciding when to force files to disk.

Of course with the ext4 developers telling people to call fsync() every time they write to the disk it may not make any difference in future.