As I'm doing an MSc course at the moment, so having a reference tool will be very handy. At work we have recently had Reference Manager installed, although I haven't managed to use it yet - there will be a training day in September and I decided to wait for that so I won't have to waste time trying to work things out.
As with Thing 13, I can't download software at work, so I will have to try these out at home, although I've had a look at the webpages.
Zotero looks brilliant - I have Firefox at home, and it will be easy to add. It would be good to have at work, too, but that's not possible at the moment. I really like the way they've made it so simple (at least according to the video!)
Mendeley looks good, with the added bonus of the social media aspect. I'm not sure how this will work in practice, and it did seem aimed more at scientific research, but definitely worth downloading to see. Zotero does seem like it could be better for more general research, and it looks like it interfaces with the web more easily.
I can access citeulike in work, and it doesn't seem to have as many bells and whistles as the previous two, but could still prove useful, especially for sharing with colleagues online.
All of these reference tools could be useful in particular for literature searches. It could also be something mentioned to research staff as it can help them collaborate with colleagues.