I found a really good example of mipmapping. I remember I used to play the game Minecraft, and I once looked at the texture map files, and noticed that there were different sizes for each texture in the game. Minecraft is a game that implements mipmapping. Here is a video that demonstrates it really well.
The difference is really impressive, and you can really see the effects of aliasing, especially on the blocks that are of high frequency, like the dirt blocks and trees, which have textures that have different alternating values tightly packed.