Stephen Boone Mini Planes
There is a set of these at the shop where I'm taking my guitar building class and they are wonderful planes to use. Both the flat bottom and curved bottom are a little bigger than my thumb. Blade alignment can be a little tricky the first few times using them but once the blade is set they are incredibly smooth. While they are designed specifically for lutherie a small plane like this is easily used for fine work or in tight spaces. I did have a few issues knocking the wedge out but with a little adjustment to how it was held that went away. They are also small enough to be pushed or pulled with no problems.
Pictures of shavings & planes in use are on my flickr page
for the class.