I highly recommend the TI-30X series of calculators. The layout is second nature to anyone who has used the TI-83/84/89/90 series and intuitive for anyone else. It maintains the 2-line screen, where you can see the data you've entered on the same screen as the calculation and scroll through past entries. It does roots, trig functions, and logarithms without graphing or solving equations symbolically (like the 89). It has a very primitive memory, with A, B, C, D, and E that can be set to numerical values. This is handy for running the same formula at several values but could not be used to store notes anywhere (though perhaps a multiple choice letter string could get out in one; if you're doing multiple choice you should be doing several exam keys already to reduce over-the shoulder copying). You can also wipe their memory between tests easily by going 2nd >> Reset >> Yes(enter).
They're $12 at walmart (( http://www.walmart.com/ip/Texas-Instruments-TI-30X-IIS-Calculator-Morpho-Blue/14918006 )), and easily cheap enough to stick on your students' reading lists, or require any primitive no-memory calculator and carry backup enough calculators for 15% of the class. I had a professor that would rent calculators to students for $1/test. Seemed like kind of a dick move even though it isn't really, but I understand he makes $10-20 per test period off it, and could put that toward recouping his investment.
As far as digital translators, etc, I have to think you should not allow in devices that can store text or reach outside networks. I have some sympathy for second language students, but networked devices in testing areas is going too far. Particularly since you couldn't be expected to tell a realtime email/text correspondence in Korean from a set of harmless definitions. If you can come up with a reasonable middle ground, by all means do it, but do not allow networkable devices into classrooms.
On a side note, I do applaud the open book testing format. It's more applicable to the non-academic world, and it forces testing on processes rather than information regurgitation.