I noticed that some of you cross-train in other martial arts.  So, who cross-trains and in what style?  And if not, what style would you like to do?

I don't currently cross-train, but I love all manner of combat sports and self-defense.  At the top of my list would be hapkido, because it's not that much of a stretch from TKD.  Boxing is more feasable, and I'd give that a go.  I'm also a sucker for military-based stuff (krav maga, sambo, MCMAP).

I don't officially cross-train, but I do observe manoeuvres from other styles and see what I can incorporate.

Muay Thai and Escrima mainly, but we started with Karate and have done some Hapkido.  I will be the first to admit that the Muay Thai sneeks in to the TKD more than it probably should.  An elbow here, a knee there, wanting to strike to the face.  Since GM Kim doesn't let us spar full contact (light or no contact only) the only real sparring we do is in Muay Thai.  Someday we'll be back in a class that will let us go full bore and it will be interesting to see if fall back to our TKD roots.  I still have no ground game, in a self defense scenario my best hope is to end it from the stand up.

BTW when we did Hapkido I thought like you that it would be real close to TKD and was surprised when it wasn't.  HKD has its own style of kicking and target selection not to mention about 10000 versions of one step sparring but no forms.  If I was going to pick an art more similar to TKD so that I could build on the foundation that I have, it would probably be Taekyon or Kuk Sool Won.

I think that anything that helps one fight in a simulated real life setting will help their training. Now one must train in a school that allows this setting to be practiced. This is of course how one learns to develop SD skills.

having some friends who are pro mma fighters, i train with them 2-3 times a week.  when we spar, we don't go all out - we either put on 16 oz boxing gloves and spar (with kicks), or we do take down and grapple.  whenever one of them has a fight coming up, we do put on 4oz gloves and go all out from sparring to take down and pound. 

they all had trained in one style extensively before they started mma (judo, wrestling, jiujitsu, boxing, and muay thai), so we take turns teaching each other. 

we also train with school wrestling team, and even though their method and point system is somewhat useless in the ring or on the street, we find training for wrestling itself is very physically demanding, so we keep up with it - also, half the guys in wrestling team have trained in martial arts (few different styles of kung fu, karate, and judo), so they often come to our training. 

with so many people with so many different skills, we learn something new almost every time we train. 

If you count wrestling as a MA, then yes I cross train,  I wrestled before TKD so a lot of my SD is more grappling based.  I'm trained in three styles and am currently coaching at a local high school.

I'd like to study some weapon based arts but no place arounds me teaches thoses

I do Brazilian Jiu Jitsu at least once a week and a MMA striking class once every other week.

The striking class is a killer workout which I love. I need some serious work though when it comes to my boxing skills.

It's taken some time, but I'm starting to love Brazilian Jiu Jitsu. During a MMA sparring session, I was in a bit of trouble during the boxing portion so I grappled and got my opponent to the ground, where I felt I had a little more comfort--but again, I know I need to work on my boxing skills.

Oh yeah, weapons.  I dabble in nunchucks and escrima sticks.  Nunchucks are required in our school, otherwise I'd never touch 'em.  There's not much stick training available to me, but it's interesting enough to keep me practicing and doing online research.

My training is a bit more interesting perhaps.  I earned high ranks in both Shaolin Kempo, and Kempo Karate.  I also trained in Dragon Kunfu and kickboxing. 

Currently I am taking TKD, however aside from poomse my training is a mixture of the styles. 

For the most part I had no intentions on taking more then one style, however do to moving and things not being geographiclly convenent I had to swtich schools.  I tried to find schools with simular styles, however starting off as a white belt in Shaolin Kempo after I earned my 3rd dan seemed like a huge waste of time for me, and honestly the program was not that impressive. The prices a very foolish person wanted to charge me for Shaolin Kempo in Wichita Ks was almost as funny as the instructer themselves.  Some people think very highly of themselves and want to just make money from people.

The one thing I like about Taekwondo is that as long as I go to a WTF school my rank should be honored so I will not need to start from white belt all over again.

In the end all of the styles I have trained in have been striking arts so the only things I had to worry about is learning a diffrent name for a technique and learning new forms.  The only real differances is the styles histroy and philosophy which I personally value, however I notice a great number of people taking classes at martial art schools widely overlook.  If you talk to people about thier art, their lingage and so forth you will get blank looks amd confused answers.  (This is something I have done when checking out possible schools in Wichita Ks, as well as Las Vegas NV and I was shocked how many students could not answer simple questions about the art they trained in. 

Started in Judo in 1971, and segwayed into TKD in 1972. In 1975 an accomplished JJ guy came in to improve his striking. When we saw what he could do if he got a hold of us we decided to "suck" as much stuff outa him as we could, continuing to train with him over the years and getting certified thru the USJA Ju Jitsu division when he became it's chairman.

While in College the school was a typical TKD /  Hapkido School so there was Hapkido exposure which gave me a good foundation to attend sessions with Kwang Sik Myung, Ji Han Jae, and some others. In Sun Seo was beyond my level.

There was a "Karate College" hosted in Chicago where Joe Lewis, Bill Wallace and Jeff Smith  taught. This lead to me hosting Joe Lewis.

Then the UFC Happened I was fortuneate to attend  multi day seminars with Royce, Rickson, and Reylson, Gracie as well as shorter sessions with Carlson Jr. (who is based in Chicago but did some seminars.)and Renzo when he  came to Chicago.

Also hosted classes by a PPCT instructor. PPCT trains police officers and prison guards. Hosted the edged weapons and Pressure point and control Tactics course.  Took some other edged weapons sessions and was able to attend Peyton Quinn's Rocky Mountain Combat Applications training Center.

 So, yeah, I guess I am a fan of cross training.