Statistics about suicide are difficult to collate, and may be inaccurate because of the sensitivity of the issue, particularly in countries where suicide is an absolute taboo. You can find suicide statistics on the following sites:

International Statistics: World Health Organisation - for international suicide statistics, including the most recent global stats by country.

The Lancet.Com - The Lancet - for international suicide articles

USA Statistics: American Association of Suicidology

New Zealand Statistics: Suicide Prevention in New Zealand

Australian Statistics: Living is for Everyone

Canadian Statistics: Canada Statistics Agency

UK Statistics: Samaritans UK provides statistics for the United Kingdom and the Republic of Ireland.

Mind - useful fact sheets on suicide statistics
University of Oxford Centre for suicide research
Office for National Statistics - trends in suicide rates