I did the analysis the other day… well, I say analysis. I plugged it into my machine (write-blocked) and basically nothing. Its all hidden or encrypted by Sony. I found somewhere that if you want to view the internal mem you need a Pandora battery, put the battery in, plug it into PC, with power cable, then remove pandora battery and put in original battery and hey presto. But since we don't have one of these batteries we can't do it.
I found a history.dat file, but there was nothing on it and it was only 4kb too. I also found, in my infinite research on this! that nothing gets written to the .dat file if the PSP is turned off mid browsing/use. It needs to be shut down correctly for history to be stored.
So overall, I learned a few thigns (that I have now shared!) but nothing on the PSP or the memory sticks with it.
Thanks for all the responses and links.