to be cheesed off that a good friend who has not contacted me in a year, or acknowledged her b-day presents etc now wants me to sponsor her in a charity swim?

[wheelsonthebus]

maybe i am just being miserable....but hey, what happened to the odd 'how are you?' or 'thank you' email

I would ignore her request. You can always give to charity anyway.

Oh enrages me when people do stuff like this.
I just ignore it completely.

yanbu

Sometimes go a long time without getting in touch with friends, it happens, but I HATE it when I send someone a present and they don't say thanks or even acknowlege receipt

That would REALLY annoy me.

Is she swimming for a good cause?

YANBU, BUT why not be a wonderful virtuous person and sponsor her anyway?
(Only if you agree with the cause, of course - not if it's for the Retired Serial Killers Benevolent Fund or in aid of the British National Party.)