That 8051 is a beautiful machine!
For applications you should be able to just type something into Google, like "8051 Code Examples", or "8051 Applications", etc. There are tons of sites out there with code for the 8051 MCU. It's a very popular microcontroller.
Just for the record New Micros sells a really nice single board 8051 complete with 32k RAM and a ROM monitor for only $39.00. It's called the NMIY-0031. It is expandable to 128K of ram by just plugging in chips. The sockets come already on the original board. Even the ROM monitor is socketed in case you want to replace it with your own PROM.
I have three of these boards.
I would also recommend the green book, "The 8051 Microcontroller, Architecture, Programming, & Applications." It's kind of expensive at $65 at Amazon.com, but you might be able to pick up a cheaper copy at a used book store. I think I paid about $3 for mine.

There are also a ton of other books on the 8051.
By the way, that New Micros board comes with four different languages on disk, C, Basic, Forth, and Assembly. Athough I personally only work in assembly code. It also connects to the serial port of a PC real easy.
May I ask what you are planing on using the microcontroller for? I'm using mine for robotics designs. Although I haven't been working on them all summer because of other projects.