Oh well... going on with the plot where it ended wouldn't be too bad to get into it.
However for a stand alone movie a complete new story - I mean not linked to the series - would be best. It could be easer to the audience that hasn't seen the last season.
Many PEELers have collected their movie ideas in here
And here you have all threads in the general disscussion that cover the topic movie
Welcome to PEEL, benderfan3k5
Don't be upset if this thread'll be closes soon, since there are already other ones covering your request. Many topics have already been discussed before, so it is best to search before opening new ones. You'll find the search function on the top right of every page.
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. They aren't not that many, and iti s quite easy to read as well.
After all enjoy your stay here. ...btw, don't use the finger smiley too often