Obviously your donation helps to move this project forward, but there's more benefits for faithful supporters. ;)
For starters, we will list you on our Contributor's Eternal Wall of Fame which is a place where everyone can see that you have a special place in your heart for this project. We wont list the actual amount you donated (it's not a battle, we're just supporting a great project, right?) but loosely organize it on the category you fall under. No matter how small or big your contribution is - we love you for it.
Secondly we will open up a special Transport Provider for you (and provide easy instructions, of course), where feature and in-development releases of HandyMan will be made available roughly two weeks prior to public releases (though we will push out security fixes to everyone as soon as possible). While mostly functional and merely a pet project, this private transport provider will get an overhaul in 2012 to provide more stability and security.
We are also on the look out for ways of giving you actual value for your donation. If you encounter problems installing or configuring HandyMan all you need is one email to get support from the developer, and we may start offering theming / extension support and development in a future release... if you have anything you think would be awesome, let me know! (firstname.lastname@example.org)