Not really. There are very few pokemon I would give a nickname too. I call Luxray by the name of Shadow, Shiny Execidrill(spelling) with the name Knuckles, and a Shiny Dragonite with the name Yoshi. I'm very bad with names and most of the time I think nicknaming them is pointless.
Yes, I gave a water related nickname to my Mudkip. ^^ It's also the same meaning as another name and is a nickname of somebody from one of my favorite groups, so that's cool too. ^^
I ALWAYS nickname them unless I'm not going to keep them. I usually just name them after characters that remind me of the pokemon, but sometimes I get more creative than that. I never accept traded pokemon unless they have a nickname either. I don't even care what the name is, I just hate having pokemon without nicknames.
I'd like to nickname all of my Pokemon, but it's hard to come up with interesting ones on the fly that I haven't already used elsewhere. Maybe I should just switch back to real word nicknames. Hmm.
I usually do when I first start the games, but after catching a dozen or so pokemon, I get too lazy to sit there for 3 minutes trying to come up with a nickname for each.
My female Grovyle's nickname in AS is Clover and I think that's super cute, I'm proud of myself for that one.
Well, I did try giving nicknames to my Pokemon in Pokemon X, but I gave them pretty stupid and lame names. I guess the reasoning behind me not giving nicknames is because I'm not creative enough to think of a good nickname. :/
I suppose giving nicknames would make the game more personal, but I doubt I can think of good nicknames for six different Pokemon.