RSS feeds - Had big problem with these to begin with until I realised I was trying to import them from the wrong place. Have to remember to look at them regularly or it defeats the object of having them. I prefer email updates.
Doodle - Loved this. Easy to use and a great way to set up meetings. Will be using Doodle to organise the rota for Saturday invigilation this year.
Google calendar - Loved this. Very simple format, easy to add, delete or change events and can be shared with other people. The only drawback is in having to access it via your Google id so am less likely to remember to use it. A paper calendar seems so much more convenient day-to-day.
Twitter - Full of irrelevancies. I like the brevity of the posts, some people may be more likely to read a few sentences that get straight to the point than an email or blog. We have a Library Twitter account that we should try to publicise and keep more up-to-date.
Flickr - Loved this but can be distracting. Gave me much more choice of photos to illustrate my blog with. Felt like a kid in a sweet shop. Could search for only those with Creative Commons and had clear guidance on what you could do with the photos copyright-wise.
Slideshare - Rather unsure about this. Wouldn't be the first place I would look for presentations, the company/institution/personal website seems a more obvious place.
Delicious - Very useful. Like a massive electronic personal desktop. Like the fact you add your own tags which are searchable. Everything is added in chronological order so no need to organise and sort things yourself. Will think about creating one for the Library.
LibraryThing - Good for personal collections of books. Easy to search for books and add them to your own private library. Can share collections and recommendations with other users. Less relevant to a library as you woudn't want to create a retrospective of your stock.
Facebook - May be an effective form of communication as I suspect most of the students have an account but on the other hand would they want a Library prescence on there? From our point of view it would be yet another thing to keep updated but we will ask the students in the next satisfaction survey if they would look at a Library page.
LinkedIn - A professional social networking site with CVs as opposed to personal profiles like Facebook. More relevant to the business world than the library community.
Zotero - Fairly simple once I had downloaded Mozilla Firefox and worked out how to drop things into my reference list. Will experiment further with this and also try Endnote and Mendeley for comparison so that if I'm asked about citation managers I can make a confident recommendation.
Googledocs - Good way of producing a document that requires input from others. Can be sent to selected people with the option to allow edits or just view. Had difficulty opening a document sent to me. May be useful when producing our library committee minutes.
Podcasts and Youtube - Listened to some interesting podcasts. Liked the library tours which could be downloaded to an ipod etc. Can download talks and radio programmes that you've missed the first time. Enjoyed Ninja Librarian on Youtube. Lots of fun and can distract you from work.
Wikis - Similar to Googledocs but on a much larger scale. Anyone can edit the content on a wiki which can be an advantage or disadvantage depending on the accuracy of the information. Wikipedia is the most famous but some of the infomation needs to be taken with a pinch of salt.
I think that more and more people are using Web 2.0 technologies to share information and communicate with others in different ways and libraries are becoming a part of that. The trick is to find which ones are the best for your library and the audience you are trying to reach.