Back when I was studying for Level 2, I wore down my awesome, trusty 電子辞書, the Canon wordtank G50, to the point of breaking it. This was during the olden days, when smartphones with multitouch screens were still a figment of Steve Jobs’s imagination. Nowadays, there are many Japanese language learning apps available on iTunes, and if you have an iPhone or iPod Touch, it’s more cost-effective and convenient to download them than to buy a separate electronic dictionary (unless you’re really hardcore).
The best app I’ve tried so far is Japanese, which basically has everything in one package: dictionary, kanji look-up, animated stroke orders, handwriting recognition, and even quizzes by JLPT level.
Those looking for a free but equally good alternative can download imiwa? (formerly Kotoba!). I think it pretty much has everything Japanese has, except for the quiz feature. It’s twice the size of Japanese, though (around 180+ MB), but I don’t notice any lag in response.
Lastly, there’s 英辞郎 on the WEB, another free app. It provides a mobile interface to SPACE ALC‘s invaluable online dictionary. The downside: it requires an internet connection, unlike Japanese and imiwa?