Hi Moomin
There are a number of wiki type interfaces out there that you can use - ranging from wikispaces, pbwiki, twiki, swiki and Mediawiki. The last of these is the one used for Wikipedia and is nice in terms of controlling layout, users, etc. but would not be ideal for novice users. pbwiki and wikispaces are probably the simplest ones to use for novices and short-term projects. There are, however, many issues you need to consider if you wish to use a wiki for research - if it is as a simple 'sharing' domain, fine - not too many issues - if you want to use it as a repository to collect info - lots of ethical and privacy and copyright issues to consider.