Tipster Mike Demers suggests that users manage their AutoCAD block libraries with tool palettes.
"Use tool palettes to store your block library. With tool palettes you can quickly redefine your blocks in the drawing. A quick way to redefine a block without going through the trouble of issuing the Insert command and browsing to the specified file location is to right-click on the block in the tool palette. The block must already exist in that drawing. If it doesn't, the Redefine options will be grayed out."
Notes from Cadalyst Tip Reviewer Brian Benton: Tool palettes are very easy to set up and to use — simply drag a block onto a tool palette tab. Once set up, a tool palette can be exported so that other users can import them to use. The blocks are referenced and therefore can be maintained, ensuring that every user gets the proper block. Once in a tool palette, a block can be set to be inserted on a specific layer. Right-clicking on the block in the tool palette brings up many options.