I've heard about WP-powered sites getting flooded with trackback spam of late. I've been hit, but it's nothing I would call a "flood". I've had spam-fighting tools in place for a while, specifically for comment spam, and those seem to work great. I'm assuming they're killing off most of the trackback junk heading my way, but I have no way of seeing that comparatively.
So, my question: How much trackback/pingback spam have you gotten, before and after installling spam-blocking plugins? Has it been a trickle (3 or 4 a day), or a true flood (hundreds daily)?