The following worked fine for me
UK, prepaid Micro sim, carrier = 3, 10 pounds 1 month, 1 GB. You can top it up on next trip
Norway, prepaid Micro sim, 100 NOK (usd 18), Telenor, you get charged 10 NOK for each day you use data. Must show passport to buy.
El Salvador, Prepaid SIM, cut it using cutter purchased @ e bay.
Carrier Tigo and Claro. Note: Using Tigo, you MUST click cancel when you get message asking for cell phone configurations.
Guatemala and Honduras, 99% sure it will work the same as for El Salvador. Will post confirmation once I have tried.
USA, signed up for ATT with USA based visa card, most probably will use Virgin prepaid MiFi in future trips to USA.
Costa Rica, going there next week, if I find a solution I will post it.