I gather assessment and other resources from maths teachers around the globe, and make them available as either text files (where applicable) or as Word 6.0 documents (if they include tables, equations or graphics).
I haven't had any problems with security (eg kids snooping around) and would be very surprised if it became an issue. Once the database has a reasonable size, it would be an extraordinary student who did all the assessment items in the database on the off-chance that one of them would appear on the test!
If this idea catches on (and I certainly hope it does) I will certainly be asking the authors of good questions if I can put them into my website.
Rex Boggs Glenmore High School Rockhampton QLD Australia