Help for first timer with unlocked phone
 

In the past when I traveled in Europe, I just turned on my international data plan with verizon and for a small fee I got 5Gb per month of data. This allowed me to retrieve email, surf the web, and tether my blackberry to my laptop. Now, verizon has reduced the monthly limit to 75Mb, which is about one days use on my corporate account.

So, I just had my BB unlocked and need advice on what to do to get the right SIM card and where. I will be spending a week in Barcelona (starting on Monday), then be in Italy, Greece, and Turkey, then back to Barcelona for a week. I don't need to use the phone for calls, just data. 2-3Gb should be enough, maybe even less as I can get some WiFi in Barcelona from friends.

Any suggestions would be greatly appreciated.

You seem to have two problems in my mind: (a) multiple countries; and, (b) Blackberry. Data is always more expensive when you cross borders. Vodafone's Data Passport is your best bet, but 3gigs of data is a lot. Their plans make out at roughly 300 megs for about 175EUR (depending on the country). iPhone Trip could be an option. I believe that they can turn Blackberry functions on as needed:

Benefits of using iPhoneTrip - 3G Internet SIM for 200+ countries, 1Gb to unlimited roaming data plans, 24/7 support