I am not too good with formulas but i have a workflow and i need to create a formula on my field update that will update my custom field "End Date" 10 years ahead in the future.
You can use addYears() method of DataTime.
DateTime newDate = System.Now().addYears(1);
DateTime Methods documentation: http://www.salesforce.com/us/developer/docs/apexcode/Content/apex_methods_system_datetime.htm
Hope this helps :)