[HoosierBrew]

My only worry now is that the pellet hops will come apart and get through the cloth sack adding a lot of debris in poured glasses. We shall see...

If some debris does come through the cloth, it'll settle. If you can find a fine mesh nylon bag at your LHBS (or use a paint strainer bag from a hardware store), it'll contain pretty much everything. No worries.

[Iliff Ave]

Cool. I have paint strainer bags that I use when transferring to the fermenter that I probably should have used. These 'cheesecloth' type hop bags were laying around so I just grabbed one. They seems to be a bit more fine than actual cheesecloth and the hops are packed in there pretty tight. 

[Pinski]

I like to use whole hops in a hop sock tucked behind the dip tube.

[dkfick]

I use one of these... so far max I've put in is 8oz of pellets at once... still had extra room... You do get some hop material in the bottom of the keg... but after the first pint or 2 you'll get hop free beer... Would obviously not have to worry about that if you use whole hops...

http://www.stainlessbrewing.com/Dry-Hopper-and-Hop-Spider-kit_p_167.html

[Joe Sr.]

I bought stainless tea balls about 10 years ago that fit through the neck of a Better Bottle.  I'll use four for dry hopping tied off with floss so I can pull them out.  They work just fine in a keg.

You can also get a stainless tea infuser which is larger and made of mesh that would work well in a keg.  More exposed surface area and all that.

[bucknut]

I use a stainless steel screen that fits over the bottom of the dip tube, got it at my LHBS for about 5 bucks. Just toss the hops in commando, first pour some trub/hop material but after that it's clear all the way to the end.

[fmader]

I hang them in a stocking with a piece of mono fishing line from a piece of stainless with a hole in it that are welded to the underside of the keg lid. I had the same issues with leakage. It was really hard to believe that 4 lb test fishing line would cause it to leak.