This week in my classes, I've been doing group projects worth 20% of their final score.
The students could go in groups of 1-5 people. I always hated group projects in school, so I like to give the option on going alone (maybe only 1 person/class chooses this). They have to choose a problem such as global warming, eating junk food, human rights in North Korea, etc and make a poster about it that's worth 10%. I give points for things such as how beautiful it is, English writing on it, and grammar.
Then, they have to do a presentation about their poster worth 10%. I take off points for reading from a script, and copying from the internet and give points for interesting and clear speaking. Each student in the group has to talk for 1-2 minutes.
Results so far? Quite good. The students have done some amazing posters and there is always at least one group in the class who does a fabulous presentation. They seem quite happy and proud of themselves when they're finished. And not that it's all about me, but it has been a nice break from being up at the front and doing lesson plans for the week :)
I did this assignment before, a couple years ago but I was much more rigid with the groups and made everyone be in a group of 5. This time, by being flexible, it's caused me much less stress and made it a much better experience for the students as well because they can just go with their friends and don't have to work with people they don't want to.