There are a lot of great ideas for displaying Lego minigures. Brickblogger put together a nice compilation of ideas so no need to repeat those.
Here are a few more suggestions.
Clear Acrylic Cases:
This is from Brickdancer. I forget exactly where he picked up this case, but you can find something similar from Joanns, Michael's and The Container store. Pretty much any hobby store.
I really like this tiered case from LegobrandonCP:
Which is similar to this case from the Container Store - plus it's only 9.99.
Here's another great version from Notenoughbricks:
The cases he used were from AC Moore but unfortunately, it doesn't look like they make them anymore.
Golfball/Shot glass Display Cases:
Very convenient for displaying a select number of minifigures. The best part is that these cases are "minifigure" ready so there's absolutely no work to be done.
Here's something similar from Michaels.
There are lot of creative solutions out there (just head to Flickr and search for Lego Minifigure display or something similar). It's just about finding the one that fits your aesthetic, space and budget.