Shovelware is difficult to define, but most gamers would say that they know it when they see it. The term used to refer to all of the extra junk programs that would come pre-installed on a PC or bundled on a CD-ROM.
Now, it increasingly refers to quickly-produced games that seek to cash in on a console's popularity, by emulating other more successful games or latching on to the latest craze. Pretty much every console on the market has titles like this – even the original NES had a raft of games that circumvented the "Nintendo Seal of Approval" in a bid to make money.
With the incredible popularity of the Wii and DS consoles, Nintendo once again finds its systems host to many titles that might fall under the category of "Shovelware".