Polls made in polldaddy.com can be embedded in the forum. You'll need to sign up for an account there first.
Follow the instructions to make a poll. Choose the questions you want, expiry date, design etc, then save it.
Once you're done, find the Embed & Link option and grab some code. You can then post this into a message and it'll appear automatically.
Please note that all you need is a direct link to the poll. Polldaddy sometimes gives abbreviated links that may not work. So, instead of adding (which is given if you choose the Direct Link code), you need the fuller version, eg http://polldaddy .com/poll/5014000/ (you get the second link by loading the first one in a new browser tab/window). Alternatively, at the time of writing this, the Posterous embed option gives the full URL that you need, so try that.
1 May 2010
12 November 2009
19 September 2010
4 December 2010