I've been having a tinker about with Google Drive and although it is early days yet, I do wonder if this could be useful to me imminently. In my voluntary position I have been helping out with accessioning new material and my mentor has mentioned that he would like to streamline the process by creating a series of spreadsheets to input new accessions data and what not (moving away from some of the paper based records that are currently kept). Google Drive's spreadsheets could be helpful here to enable multiple staff members to contribute to this process and help to refine it... might be worth a go!
Dropbox is also new to me, but have to say I find myself oddly fascinated by it (have caught myself cooing over 'the clever little thing'...I worry about myself sometimes!). Definitely something I will make more use of!
What to say about Wikis beyond the obvious Wikipedia references? I do rather like the idea of collaborative work to help build up information and pool ideas and knowledge- i.e. enabling everyone to have their twopennys worth! I cannot at this stage claim to be ready to take this particular 'bull by the horns' and start my own Wiki, but in the future I think I jolly well might!