I just went through all of my JOSM plugins that I have installed now and wrote down comments on each of them for a workshop I have coming up. I also threw in a few comments on Plugins that I remember having problems with in the past. Since it's way to long to use in my presentation I figured I would post it here.
The plugins I use the most are now in bold and I'm also going to update this list if I start using more plugins.
dataimport if you dig a little you will find out that it only supports TangoGPS and Garmin Trainings Center TCX file formats or at least that what it says in the readme file and here on the Wiki
ElevationProfile Can be helpful when determining if a street is on an incline or decline.
FixAddresses Not very helpful because if a building has more than one node each node is listed as having its own address. So the list it create are often to long to be useful.
geotools - Was installed by another plugin
GPSBlam I haven't spent enough time with it to know how to properly use but it sounds like I should.
GPXFilter I'm not sure if this is needed or if it is installed by default.
ImageWayPoint - I might be using it or I might be using another plugin that does basically the same thing I'm really not sure.
InfoMode Can be helpful when dealing with multiple GPS traces a the same time.
jts - Was installed by another plugin
Kendzi3D-jogl - Was installed by Kendzi3D which often caused JOSM to crash so I uninstalled Kendzi3D but it must have left Kendzi3D-jogl behind.
log4j - Was installed by another plugin
MapDust Sounded like it would be really helpful when I installed it but I haven't been using it.
measurement - I haven't found this to be very useful
namemanager - It sounds like it might be helpful but it doesn't work the way I thought it would and what it does do isn't helpful
OpenData I think I was trying to use this to added some missing towns that are around Syracuse but after reading the WARNING on the WIKI I decided not to use it.
[OpeningHoursEditor](wiki.openstreetmap.org/wiki/JOSM/Plugins/OpeningHoursEditor) Makes it easy to set hours for businesses but it should obviously only be used with businesses that have constant hours.
OpenStreetBugs I haven't really been using it but I don't know why.
openvisible - I don't think it works
[Photo_Geotagging](wiki.openstreetmap.org/wiki/JOSM/Plugins/Photo_Geotagging) Very helpful for making GEO tagged on photos more accurate by default on my Android phone the photos are really off so I would correct them before they were uploaded to OpenStreetView.
print - Helpful if you need to print parts of the map but don't try to use it with an area image because things wont line up properly.
restart - Helpful when you install as many plugins as I have
Reverter Sounds like a good idea but I don't think I've used it since I've installed it.
[RoadSigns](RoadSigns http://wiki.openstreetmap.org/wiki/JOSM/Plugins/RoadSigns) I was trying to add some deer crossing signs which I didn't end up doing. It doesn't help that the only country in the presets is Germany.
Tag2Link Helpfully when adding wikipedia page because there supposed to look like this "wikipedia=en: U.S. Route 11 in New York" and not just a url
turn_lanes#Plugin Could be helpful in the future but should not be used now because it uses a relation that has not been implemented into the API and if your not sure if you should use a relation
TurnRestrictions Anything that makes dealing with relations easer and safer is great plus turn restrictions are also one of the few relations worth messing with.
Undelete Sounds like a good idea but I don't think I've been using it.
UtilsPlugin2 Should be installed by default
VideoMapping Sounds like a great idea but it always crashes JOSM for me.
WayDownloaderPlugin isn't as helpful as it sounds like it's going to be.
waypoint_search - Makes finding all of the tags I recored much easer especially when I'm using the Bing satellite images
Wikipedia It should help you find wikipedia pages but it doesn't seem to work for me most of the time
Ok the really crazy thing is that I haven't installed all of the plugins so if you used a plugin that you think is great post a comment about it or if you have a similar list post a link to it.