People have been asking that for a while now...
In climbing there are several different rating systems. Here in the US we use 3 rating systems depending on the type of climb. For regular climbing they have ratings that look like 5.10a -- these start at 5.1 and go through 5.15c (the latter being climbed by only one person in the world -- and many people wonder if it truly is a 5.15c...). For this type of climbing, the hardest I've done is 5.11d -- I've started working a 5.12a tho. On a regular night I can climb 5.11a fairly easily.

In bouldering they rate the climbs with a V system -- it starts at V0- and goes up to V15. A V0- is comparable to a 5.10a. A V15 has no comparable roped climb -- it would be somewhere around a 5.16 or so. They are a lot harder but also a LOT shorter.

There is also Aid routes -- you'll see ratings like A4 5.10a -- this is a way hard aid climb -- where you are actually using placed gear to stand up and climb (typically in cracks that you can't fit your fingers in -- much less a foot!).

So that still doesn't explain a lot. But here is a short video Windows Media (4.9mb) or Quicktime (for you mac freaks) (5.0mb) of the my first V6 that I completed.

*That* is a V6