You can use Paypal or Flattr and write a script that keep track of payment by yourself.
Hacking a donation button wouldn't do much, since it's basically just a link to your choice of payment processor's donation page. They'd have to hack that payment processor to get to your account.
You could also go with an e-commerce service and make each perk/reward/options for donation one item instead. This would be better in term of keeping track of who support you with which option, since e-commerce service comes with statistic tools as well as automatically keeping record of your customers.
For a button and a meter, Chipin is one of the services that does this for you automatically. http://www.chipin.com/overview