I added Trackback from holascan to my site a while ago, but have since taken it off due to complicated pinging and nobody ever referencing me. All it ever did was take up room.
However, IceRocket has released a fantastic service called LinkTracker. It is effectively the link at the bottom of every post that says "# LINKING POSTS". If you would like to see it in action, just look at my IE7 Sucks post. You can see that 2 other blogs have referenced mine. I know (!) isn't that amazing. Oh yeah, I hope you can read Spanish too because apparently the only people that will ever read this post happen to type in Spanish.
Its not perfect, actually the first Spanish blog to reference mine was Minid.net. IceRocket doesn't acknowledge this blog for some reason. Oh well, it can't be perfect if its free, right? I would recommend putting it on your blog if you ever think that maybe, somebody, somewhere, sometime, might reference your blog. Because, then you'll know who they were. :)
oh yeah, IceRocket also has this fun new thing called Trends. It tell you what is more popular in the blogophere between any two terms. Give it a spin if you like: Bush VS Blair.