<p>I've been playing with RSS feeds this week, and for my next trick I want to build one for our internal application log.  We have a centralized database table that our myriad batch and intranet apps use for posting log messages.  I want to create an RSS feed off of this table, but I'm not sure how to handle the volume- there could be hundreds of entries per day even on a normal day.  An exceptional make-you-want-to-quit kind of day might see a few thousand.  Any thoughts?</p>

Without knowing your application, I can't offer specific advice.
That said, it's common in these sorts of systems to have a level of severity. You could have a query string parameter that you tack on to the end of the URL that specifies the severity. If set to "DEBUG" you would see every event, no matter how trivial. If you set it to "FATAL" you'd only see the events that that were "System Failure" in magnitude.
If there are still too many events, you may want to sub-divide your events in to some sort of category system. Again, I would have this as a query string parameter.
You can then have multiple RSS feeds for the various categories and severities. This should allow you to tune the level of alerts you get an acceptable level.