While wandering round the internet during the recent flare-up of bloggers writing about recent developments in the MMR-autism conspiracy theory, I came across this neat graphic which seems to me to encapsulate some of the issues relation to causation vs coincidence (for example, see "MMR and false syllogisms" for more information).

In the meantime, Ben Goldacre’s Bad Science blog seems down – maybe the recent upsurge in traffic has overwhelmed it.