As you might know GO is using Q2A for running this site. So, now we are requiring many features to be added and one of them is the ability to add new user field types mainly Checkbox and DropDown Box. So, if anyone is capable he/she can do it. The code is in PHP/MySQL and plenty of examples you can get from the below link. This plugin if done well will be contributed to Q2A site as opensource but you will be paid Rs 2000 also.
http://docs.question2answer.org/plugins/
