Earplugs for conerts?

I've done the napkin thing plenty of times. It's fine if there's no other option, but I always have problems with them leaking certain frequencies, as well as blocking certain frequencies, more than others (your crumbled napkin chunk may vary).

The rollable foam EAR-type plugs are great for blocking loud noise, but cut way too much high-end from music. They make everything sound way too muffled.

The best I've tried are the Hearos rubber tree-type plugs. I believe they are made or designed by Etymotic and marketed by another company as Hearos, so the Etymotic plugs should be almost identical. They do a good job of cutting enough volume to avoid damage, while maintaining a balanced frequency range. They allow you to hear all of the high end and vocals that some of the foam plugs or napkins cut out. They take a bit of time to get accustomed to, but they are worth checking out if you go to a lot of rock shows.

I really like my etyomatic ear plugs. Worth the $10 or so. Found them much better than foam which blocks way to much of the highs. They are not truly balanced, but how far you put them in adjusts the sound level blocked. I recomend them.
I think I got mine from music direct.

My ears seem to have a problem with ear-plugs, due to sinus pressure issues probably. They are pain-inducing so I cannot wear them. The expandable ones that you squeeze prior to putting in your ear seem to work pretty well and I can use these. Unfortunately, as folks have pointed out, it actually nullifies your connection with sounds going on about you so they won't be too good for live concerts. I use the napkin thing most often and would add a 'tweak' to this. Prior to using them, lightly dampen the napkin and press a portion of the damp portion to form a plug. Works great...fits much better and does a better job. It's important to lightly dampen and not soak the napkin though for it to work best. I usually just run some water on the back of my hand and blot it up. I use this when playing drums, mowing the lawn, some live music, vacuuming, sawing and nailing during construction, etc.