Fridrich (CFOP) Method
Sometimes, when the F2L pieces are stuck in other slots, there are shortcuts for solving them. Here are some examples. There are probably more, but I find these the easiest to do when these cases turn up. These diagrams might be confusing because they only show three sides, so check out the Java Cubes [coming soon!] for these cases if they are not clear.
|y L' R U' L R'||L' R U L R'|
|R U2 R2 U R||y' R' U2 R2 U' R'|
|R' U' R2 U R'||y' R U R2 U' R|
|R2 U' R2 U R2||y' R2 U R2 U' R2|