A vocabulary activity I've used with my students a few times is the word sort. I'm not sure if I'm suppose to credit this activity to a specific source or not. I've seen it in a few different places.
The way I've used it is with vocabulary words that my students have. They generate their own cards with words, so there is very little prep time for me as a teacher, and the activities yield high-quality learning. Simple is best--my kind of activity!
I always give students one or two closed sorts, that is, specific categories in which they should sort their words. A particularly interesting one I have used prompting my middle schoolers, asks them to sort words that applied/described certain characters. Another basic one is when I ask students to divide the words into positive and negative words. Oh, holy connotation! That gets some discussion going. Tonight in my creative writing class, the words "audacious" and "willful" started some heated debates. Fighting over words! I love it!
I think it's particularly engaging to have students create their own categories (open sorting), too. My middle schoolers needed some suggestions in the beginning when we first started using sorts, and I had to guide them away from boring sorting. I have used opening sorting differently with my creative writing students, as I usually have them write stories or poems with their words, so I have them group their words into smaller groups of words that would sensibly be used in short poem or paragraph.
What I like about sorting is that students get to work collaboratively, talking about words. They refer back to definitions, debating how words should be sorted and start to see relationships with words. I've never seen students interact so vigorously as they do with this activity.