Harai Goshi - take a look at the throw and the motion of your side kick.
Here's a well known video clip:
http://www.jimmccoy.com/judo.cfm
Doesn't this motion have a lot in commin with a kick that you know.
It is interesting to study various martial arts - cross training is an old idea, not knew. But cross training is not required to learn various aspects or ranges of fighting. Traditonal, non-sport oriented arts are complete. There is even ground fighting in Karate, atleast in Goju Ryu. You have to learn the kata and learn how to apply your knowledge in different situations.
I guess most karateka have heard the phrase "a block is a strike". Add to that, "a block is strike, a strike is throw" and strikes include kicks, so a kick is a throw.
The main difference between Judo throws and Karate throws in the off-balancing.
One of the myths that of Karate - that Uke means block - causes a lot of misunderstanding. Uke means reception - think of Ukes' role in your Jujutsu. Uke is the one "receiving" the technique - or who is "received" by Tori. Here you see a demonstration of the principle of Ju. Now apply that to your Karate blocks and "receive" uke. Here you see the JU of Goju Ryu as well as the JU aspects of other Karate styles.
Look for the commonalities in other arts as well as those ideas that are not just common but similar in motion. Then look at your karate kata and see how you can work the other arts into your kata. The chances are you will find every Aikido, Jujutsu or Judo technique that you know will be applicable some where in your karate kata.
Your home work for today is a simple assignment. Find one of your Karate kata that has Seo Nage in it. You will likely find it is a kata that you learned as white/yellow belt but went on to a new kata instead of learning this one thoroughly.