I use (Super)Karamba. I think it's kinda unstable but I like it. After taking look at GkrellM right now I found out it's not for me: I'm not a real GNOME's fan. Karamba's good. Lots of neat stuff to let your desktop just like you: punk rock, heavy metal, cute, radical, sportist, total geek... Slackware fan!
My Desktop is a big tribute to Slack. (Who sees my posts around might have noticed how much I like my Slackware....indeed, but thinking about giving FreeBSD a try... having both, you know? I know that slack's very similar to *BSDs in many ways anyway, I think won't be such a problem to get it working smoothly here)