Covering a book can be such an annoying task - especially cutting out the little square inserts for the spine. Little did you know, there is a far simpler method for protecting your textbooks.

[edit] Steps

Lay out a length of plastic wrap on a kitchen counter, table, or other long flat surface about three times as long as the book you want to cover and detach it from the roll
Place the spine of the textbook in the middle of the plastic wrap and lay it down to one side. Open the other side onto the plastic wrap and ensure the spine is touching the wrap
With the whole cover touching the plastic wrap, fold the wrap that extends beyond the book over the cover.
Finally, fold the parts of the plastic wrap that extend above and below the book over onto the cover of your book, touching the portion you previously folded.
Apply duct tape over the seam where the plastic wrap meets.
Repeat steps 3-5 with the other side of the book.
Apply a strip of duct tape along the spine of the book to ensure it doesn't rip or tear and to support the spine
Go to class with your awesome textbook!

[edit] Tips

Use colored duct tape and/or plastic wrap for a more artistic flare, or packing tape to make the cover invisible!
Apply more duct tape to the edges of the cover for more durability