Paid users can create polls in their own journals, as well as in any community journals (whether free or paid) that they have posting access to.
Polls may only be embedded into journal entries, not comments.
These are somehwat correct. It's also possible to add polls to your user info, as you can see in my user info.
How do you do this?
1. Create poll,
2. Post poll in entry,
3. View source of webpage (on either recent entries or comments page),
4. Copy the form code,
5. Edit your personal info, adding the code where you like, then save.
Simple as that.
I've been following the community for awhile, and don't remember seeing this, so I hope it's not been posted before.
Since it's simply HTML, you can make whatever modifications you desire to make it all pretty-fied or look special-like (within LJ and HTML limits). And, of course, you need to keep the journal entry once you do this, since deleting the entry deletes the poll.
Another thing to note is that poll results are not displayed automatically in the profile after completion of the poll, so you may want to leave the link to the poll results page in there for easy access (or, if you're all into the customization aspect, you can always drop that part and just click the submit button, since the following page will have a link to the results.
A simple, no-special-effects poll is visible in my user info, so you can see this in action. And, just a reminder, polls are for paid users only.
Hopefully this is considered nifty. Some thought my different approach to the friends view was nifty, but I think this is more nifty.
EDIT: Note that in order for random visitors to take the poll, you need to make the entry the poll was created in PUBLIC.
EDIT: Also, let me know if you put a poll in your profile. I'd like to see what people use it for. :)