SIPP, ETFs and iShares

I've got about 20% of my SIPP invested in the FTSE 250 which I thought was a good idea, and still do just about. I bought just after it dipped below 6000 and today it's back to about 6000 again. Despite all the severe economic news recently the 250's been above 6000 for most of the time since it first dipped below the line last November.

I'm looking at other ETFs (ishares) to see what else might be worth a punt for long term for the SIPP.

iShares - The World's No.1 provider of Exchange Traded Funds