Max...

I've found it useful with MySQL machines, to have a second,
smaller, MySQL box which mirrors the data on the first
one.

We do data analysis, backups, etc. on that machine and
that way anything I do (like an outrageous query) affects
only the backup machine.

Another fun scenario is for all writes to take place on the
primary machine, but move reads and browsing to the #2
box.

Finally...I think this thing is on the old CF Forums, which
is pretty weak in terms of performance and reliability. We've
been pretty impressed with VBulletin.