The first, most important thing you get from donating here is Lodge Points, which can be used to purchase a variety of items from the JCP's Hunter Lodge.
The Lodge points also are needed for various other things, including building Dwellings, and buying certain Mounts.
Many specialties become available to you at a certain dragonkill level AND accumulation of a certain amount of earned donation points. The specialties do not charge you for selecting the specialty...and what determines eligibility for these specialties is not on-hand, or available Lodge Points, but rather Total Earned Lodge Points.
The Mounts, on the other hand will require a certain amount to be AVAILABLE...and will charge you some points, but not as many as you are required to have available to be eligible to purchase the Mount. There are certain shops that are open only to cash donators. And these open with any donation...even an amount as small as a dollar...will open these areas to you for thirty days from when your donation is applied (so it is no problem if you donate towards the end of a calendar month...you carry the benefits for a full thirty days.
The following shops and navigations are available only to cash donators:
Sichae's Apple Shop, The Temporal Mistress, The Temple of Shadow and Light, Dianecht's Waterfall, Tim Horton's, Hikaru's Literature, Jewels by Yara, Prime Real Estate, Turn Tavern, Name Change Department.
Additionally, cash donators are able to navigate to Olympia, the City of the Gods. Also, cash donators have access to full automatic fighting in the Forest, and the Banking Eagle in the Forest. Cash donors also have access to Cedrik's Potions and to being able to bribe Cedrik. Certain Mounts are also available ONLY to cash donators, no matter how many Lodge Points you have (there are ways to earn Lodge Points other than donating.) One can play a full-featured game and never donate a dime, but these features are extra, as a way of thanking our donors.
Also there are sitewide benefits when our donation goals are met in a given month where everyone benefits. The donation goal is set based on what it costs to run this site (bandwidth is unfortunately not free...) You also get a donator ribbon in your character's bio so that everyone knows what a wonderful person you are...and, of course, who to thank when the sitewide benefits kick in!
More incentives may become available as I think up things or players come up with good suggestions.