A VPS would leave you on your own to set things up though. I have the book "Running Weblogs with Slash", and it is pretty non-trivial to set up.
What I think the original poster is asking (and what I'd be interesting in finding out about) is if there are hosts that explicitly cater to sites running Slash. This would include the basic software running, but also some degree of support.
Also, from what I've read the Slash daemon is very processor intensive, but it's fairly constant if the server has to hand a small or large load. It might be too much for a cheaper VPS account.
On the slashcode website, there's links to a few, but they seem to charge $25/month for a basic hosting plan.
I ended up giving up and using phpnuke on my site that would have been better served by Slash.