4. Twitter - if you don’t know why, see Charles Arthur‘s blog.  Add to that a mobile Twitter app like Dabr or Twitterberry for keeping up on the move.  Ditto an app such as Tweetdeck for managing your Twitter feed(s)

3. An RSS reader.  Although I spend a lot of time hiding from mine…but in my defence, most of my feeds are now delivered through Twitter

2. Wikipedia - because let’s face it, when new to PR (especially tech PR) you won’t know your operating systems from your middleware and wikis or glossary services like this will be your best friend.

1. Delicious - reading is the lifeblood of our industry but if you, like me, find almost every subject you come across interesting and have a healthy dose of ADD thrown in for good measure, this is your best friend.  It is like having a clippings book and personal researcher with you at all times. Essential.

These are just the basic essentials.  For the next stage, see Ged‘s meme that I responded to here about the new skills required but I would be put off hiring anyone not proficient in working with the sites, tools and apps listed above.