Add Donations to Event Registration Form
Simply set up an additional line item for a donation in a Price Set.

This is how I do it... the Price Set definition:


And then how the 'Optional Donation' is defined:


And a preview of this in action:



Feel free to give it a whirl on my website - and make a donation if you like it! :-)
http://www.breinton.com/book/hipp-abbate