Is there a cost effective way getting a data connection (sim card) for a mobile phone for 3 weeks while I am in Israel? So that I can read emails, and make use of google maps on my phone?
Pre paid cards data connection in Israel can be quiet expensive (for my opinion at least). From what I've seen in Orange BigTalk web site (sadly available in Hebrew, Russian and Arabic languages only), data connection on pre paid SIM costs are: 1MB = 4 NIS .
You can get those cards in Israel post offices, kiosks, and Orange service points that exists in every mall.
Currently the price for a SIM card charged with 40 NIS, costs 50 NIS (Israel post office price, other providers may have different prices.)
There is another Cellular provider called Cellcom, and thier pre paid card called TalkMan, they don't state the date connection prices on their website, but I believe both Orange and Cellcom have similar prices.
You should know that it is very easy to find a free WIFI connection. You can find one in almost every restaurant, coffee, mall and most likely the hotel you will be staying in.
I think the best solution for you is to download offline maps, or use Google Maps Pre cache feature. Read emails over WIFI connection. And additionaly buy small data connection pack for emergencies.
BTW, if you are planning to use Google Maps Navigation, it is not available in Israel yet.
Hope that was helpful.. Enjoy your trip!
If your phone is unlocked' then instead of getting a Sim card from one of the main providers stated above (cellcom or orange) it is easier and cheaper to rent a sim card (you can get also a phone as well) for the short term period you need it for. You can get packages for data usage and cheap calls overseas. you can check the prices at http://www.israelphones.com . It also makes things alot easier...
Good luck, and enjoy your trip !