aidanjit, notepad++ is very useful - thanks for the suggestion
Rosaline, I'd agree that OpenOffice isn't a competitor to Microsoft Office. I can't go without Outlook so I use Office 2007, and I'm even quite fond of the "ribbon" interface. That said, I think OpenOffice does have its uses. If a user doesn't use many office features, and his/her tasks generally involve banging together a few quick documents, I'd usually suggest OpenOffice as a first point of call.
Meebo is a good one! For an alternative desktop IM client, I've found Pidgin to be handy.
Finlay, the Live Mesh tech preview is now open to all in the US. Later today, it'll be open to all in the UK, Australia and New Zealand, too. So there will be no need to sign up to any waiting lists - you'll be able to sign up directly at Mesh.com.
Looking forward to hearing some more suggestions, always fun to hear what other people are using.