I was all set to say “Just get an iPod Touch and download Kotoba!” and then I watched the video Tom posted a link to and realized Koichi beat me to it. Well, except for the Kotoba recommendation. (For the record, I like Kotoba because it’s both free and thorough. And yes, it, too, uses the Jim Breen dictionary.)
Starting to think I need a t-shirt that indicates my status as a Koichi fangirl in training. (I promise to stay on the non-creepy side of fangirlism, though. ;))