Watch out for scams to steal your bitcoins as you spend/donate it http://evilpacket.net/
(Is this vulnerability fixed now?)
One possible solution :
If the bitcoin client supported a standardized text block containing the address & amount, eg.
then you could have a "Copy to Clipboard" link, paste it in to the bitcoin client, and click Send. Would make BTC easier to spent, as you wouldn't have to write in the amount.
Don't know how secure this is though, maybe someone can write a web script to snoop the clipboard buffer?