Not sure how many of you use a PDA. If you use Palm OS, I highly recommend these two programs:
Anki (http://www.anki.com) - a flashcard system. I used to write my own flashcards and had about 4 small boxes of them before a friend found Anki. I’ve already compiled Sh-Da’s Book 1 and Book 2 (Part I) using Anki’s database builder and uploaded them to their community forum.
Oxford Concise C&E Dictionary (http://www.pleco.com). Not an exhaustive dictionary but definitely the most common words with Pinyin, the ability to zoom in on characters for clarity, radical lookup, simplified and traditional characters, and the best feature: handwriting recognition look-up (for when you only see a character with no pronunciation key or definition).
Hope these softwares can benefit you as much as me.