There are 17 different type of questions you can ask in a Twtpoll. See them below:

Multiple Choice (select only one answer)
Use this question when you want your users to select only one of your choices.
There's also an option to let them enter "Other choices".

Multiple Choice (select multiple answers)
Use this question when you want your users to select one or more of your choices.
There's also an option to let them enter "Other choices".

Drop-down (Choose only one answer)
Use this question when you want your users to select only one of your choices.
The user has to choose only option via a drop-down box.

Matrix (select one answer per row)
Use this question when you want to ask a few characteritics about more than one item

Rating Scale
Use this question when you want rate something.
The scale goes up to 10 (you can choose the range and we'll adjust the increment).

Ranking
Use this question when you want to rank several items.

Single Textbox
Use this question when you need an open short answer, usually a couple of words.

Twitter Comment (140 chars)
Use this question when you need an open answer (up to 140 chars long).

Essay Comment
Use this question when you need an open answer (essay long).

Image Multiple Choice (select only one answer)
Use this question when you want your users to select only one images of your choices.

Image Multiple Choice (select multiple answers)
Use this question when you want your users to select one or more images of your choices.

Image Rating Scale
Use this question when you want rate an image.
The scale goes up to 10 (you can choose the range and we'll adjust the increment).

Image Ranking
Use this question when you want to rank several images.

Twitter Multiple Choice (select only one answer)
Use this question to compare Twitter Users and when you want your users to select only one @twitter_user of your choices.

Twitter Multiple Choice (select multiple answers)
Use this question to compare Twitter Users and when you want your users to select one or more @twitter_user of your choices.

Twitter Rating Scale
Use this question when you want rate a Twitter User.
The scale goes up to 10 (you can choose the range and we'll adjust the increment).

Twitter Ranking
Use this question when you want to rank several Twitter Users.