Yes, your models can be sent to a 3D printer and printed in 3D, even in colour! You can even print in stainless steel or glass! A model a few cm tall might cost a few tens of Euros. Check out www.shapeways.com .
Here is an example of an object printed on a 3D printer. It's Suzanne, Blender's mascot. I had to spend a couple of hours modifying the monkey that is included with Blender before it was ready for printing. It's about 12 cm wide and cost about 20 Euros to print at Shapeways. I hope you like it (my cat did).
Make no mistake: preparing a model for printing in 3D is much more difficult than making a model that can be viewed on a computer screen for the model for printing has to be a closed 3D surface - our model house with doors and windows would not print, for example, for its walls were surfaces that had zero thickness - such walls cannot be printed since they have no volume. A closed 3D surface can be said to be 'watertight' but there are additional requirements that are even harder to understand: the model must be 'manifest' (every edge must be connected to exactly two faces) and all the normals must point out of the the 3D surface. The Shapeways site gives lots of help in meeting these requirements, but expect to spend hours modifying your model if you want it to be printed in 3D.
A good trick for keeping the cost down is to make the model hollow since you only pay for the volume of material actually printed, but hollowing out your model requires even more work. The 'solidify' modifier is very useful for producing a thin shell. Here is a hollowed-out model of Suzanne that I made based on the built-in Blender monkey mesh (in the end this one was unprintable for its smooth surface consists of nearly half a million faces and I wasn't able to identify and fix the few faces that caused problems).
Note the hole that I made in Suzanne's neck so that unused plastic powder can be removed from inside the model after it is printed.
Watch this video to learn more about 3D printing:
Here are some good pages that give more advice about how to prepare your model for 3D printing at Shapeways, including printing in colour: