I have had plenty of experience of attending seminars, conferences and other events but have yet to experience presenting at or organising any.
I have attended courses on topics such as Advanced Searching Techniques, Chartership and interview skills.
The events I have attended in the past have not only kept me up to date with goings on in the profession but have provided me with networking opportunities.
Due to the economic climate both staff and monetary restraints mean that it is currently difficult to attend events. There is also, as others have mentioned, the geographical aspect, although with a lot of conferences, seminars and training events now being made available through web conferencing this should make it easier for me to participate.