I've got two
The Casio XD-470 allows you to draw kanji & get the meanings, which is quite useful. However, it expects the handdrawn version of each kanji. If you try to copy one from a book, sometimes it gets the wrong one because of that. You can even draw a sequence of Kanji to get a compound. However the lookup is in japanese. To get the english, you have to look at the displayed entry, remember the hiragana, then select the japanese-english translation option & type it in again. Furthermore the dictionary is very very small (in number of words). No english manual, but once you've manually translated all the menu options, it is easy enough. Overall, handy to find that unknown kanji (if you're lucky), but useless as a dictionary.
Canon G70: I was going to get a G55 when I went to Japan in April, but the first shop I went to was out of stock, but had the more expensive G70. It costs a lot more, but has a much bigger Japanese->English dictionary. It's my dictionary of choice. Furthermore the super-jump facility allows you to highlight any word and search all the dictionaries for it. Thus for a really obscure word, you can use the Japanese-Japanese dictionary, then use super-jump to look up any words you don't know in the explanation. Sounds difficult, and it is a bit. However much easier than the other option, which is not being able to look up the word. There are some other nice features, like displaying the stroke order graphically of the more common kanji. You can't look up kanji by drawing them though. Comes with a shortform english manual, which doesn't describe all the functions. I still haven't quite figured out how they all work.
I also considered (but didn't buy) the Canon V80. This is a chinese/japanese/english dictionary. It is really aimed at chinese though and the size of the Japanese->English dictionary is slightly smaller than the G55 and much smaller than the G70. The attraction is than you can draw kanji for lookup.
There's a bunch more dictionaries. Some take extra programmable modules. Casio do a big range. Don't know how accessable they are to english speakers though.
Overall I think the G55 is great value, but the G70 is better, but at a high price.