New types of adjustment layers

Does CS have a way to do adjustment layers that do either or both of the following?

1. Filters as adjustment layers
2. Gradient opacity as an adjustment layer

I'm pretty sure that the answer is no, so my follow up question will be how can one apply a gradient opacity to a layer? What technique / tools exist to do this?

I am constantly wishing that I could change the opacity of a layer gradually or with patterns gradually. I'd like to be able to apply an opacity gradient anywhere where I can currently change the opacity of the entire layer and I'd like to be able to use all of the blend modes to this gradient opacity.

1 - no
2 - can't you simply do this with a gradient on a layer mask?

2. Colin, apparently so. Masks again! I think that I am finally just beginning to understand them. Add layer mask and apply gradient, very simple.

Mike:

I much prefer using masks to selections - the two are, of course, quite interchangeable.