One of my favorite plans is the DIY Changing Table from The Design Confidential. This plan would take and intermediate to advanced woodworking skills but you would create a lasting quality piece of furniture that can be used long after your baby has grown up.
The simplest plan is from Lowes.com and it is just eight pieces of wood that you put on top of a dresser or short bookcase. The plan has good diagrams, and detailed instructions for designing this table to fit your changing pad.
thedesignconfidential.com


Attractive baby changing table dresser with two drawers and two shelves for easy storage of your baby things.
ana-white.com


A rustic barn door style changing table from Ana-White.com. No rails on the top so use a contoured changing pad on top.
instructables.com


Simple changing table that fits on top of a short bookcase. Great photos and instructions to build this inexpensive project.
ana-white.com


Well laid out Baby Changing Table Design with two shelves for baskets and plenty of room on top for a changing pad.
instructables.com


Sturdy wooden changing table with two shelves and room underneath for baskets to hold baby stuff.
lowes at archive.org


Easy Table Top Changing Station from Lowes. Well done plan with materials list, illustrations and useful instructions.
canadianhomeworkshop


This diaper changing station has three cubbies for baskets and a cabinet door with two more cubbies inside. Plan has great diagrams, good instructions and some photos.
diynetwork.com


This changing table folds into the wall and takes up no floor space. Nice 10 step project from DIYNetwork.com.
canadianhomeworkshop


This looks like an antique dry sink but is dimensioned with a recessed top and storage space that are great for a baby's diaper needs.
am-wood.com


This dresser converts to a children's chest-of-drawers when your baby out grows it. Limited illustrations so you will need to ad lib this plan some.
lowes.com


This page is missing some pictures but if you look in the right hand column you can download the Project Illustration PDF and it makes for a good plan.
sketchup.google.com


This airy diaper changing station is designed in Google Sketch up. With Google's free software you can get dimensions to make this plan. There are no written instructions.
sketchup.google.com


You can build this changing station from these Google Sketchup Plans. You will need to download the free software and it's a bit of a learning curve on the software.