This is one thing is the best way as it show how much they donated and one site do I know one site that they even got a $100 donation that they had to make a new rank in order to show the persons admiration/dedication to the site.
this could be usefull example (colours don;t have to be used)
anymoney-$5 Donator with tag
$5-$20 Reputable Donator
$20-$50 Honorable Donator
$50+ Accuresed Farms Worshiper
I just had a stupid idea, what if they were made farm-themed?
something like...
any money-$5 Unlucky Pig Sty Scrubber
$5-$20 Damned Henman
$20-$50 Cursed Farmhand
$50+ Accursed Farmer
Eh? Eh?
