The style of Aikido I practice (Shoji Nishio Shihan style) is closely related to both jo and bokken. We do most of the basic techniques with a jo in the hand to develop the right feeling of cutting with the hand. We also do them as ken-tai-ken (sword vs. sword) and ken-tak-jo (sword vs. 'stick') - a bit like two-person kata's and then we do some basic tachniqes with the jo as well. All this is to underline the fact that Aikido is developed from the sword (at least some aspects of it
In addition to this we are encouraged to practice a form of Iaido developed by Nishio sensei himself called Aiki-toho. Originally it was recogniced as a Iaido-style, but due to a disagreement with the Iaido-federation it is now concidered a whole new budo in itself. The purpose of Aiki-toho is to develop the right body posture and the right feeling inside the body when doing the techniques.
Finally a comment to Steve Nelsons post:
However, if your search leads you to Kyudo, Kendo, Jojutsu or Bojutsu then good luck
I can only second this, but since I have had some experience with Kendo I would like to add that one should be concider it very carefully before taking up this art as a supplement to Aikido. It is a very different mental attitude that one develop and I have had a lot of problems 'de-learning' some of the things that I've picked up in Kendo.
All the best