Many of the cutest patterns we run across are not free (sadly). Or they come from magazines or pattern books that were purchased. Because of copyright laws you cannot post a purchased pattern on the boards (you can talk about it all you like, just not post the pattern.)
There are tons of free pattern sites out there and if you really love a pattern from a book you can usually get the book through interlibrary loan at your local library. Old copies of knitting magazines can be found online as well.
For knit-a-longs, if the group chooses to do a purchased pattern for the project, the pattern must be purchased by everyone doing the KAL. Most patterns can be purchased for only a few dollars.
That being said, have fun and happy knitting!