Hard to be really specific to "a 30 something mother", but here's a lot of what I and my wife use regularly:
Games (which ones are a matter of preference, but there are a LOT of free & addicting games available)
Reading (magazines, websites, books, and I enjoy the puzzled looks I get when I use my Bible app at church)
Video (Youtube, Netflix, I even have an adapter on my Dish DVR so I can watch shows from my DVR, or live tv)
Web (duh)
Social networking (facebook, google+, linkedin, etc)
Remote desktop (I personally use LogMeIn Ignition, but it's kinda pricey, there are cheaper apps out there. Very handy for my business, not sure everyone would have use for it)
Maps & navigation (it's amazing how much time you can waste on Google Earth looking up random stuff... pyramids, chernobyl, paris, grand canyon...)
Music (google & amazon both have great music setups, though amazon just changed their setup & scaled back what they offer for free)
Email
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Honestly, how the tablet gets used will probably evolve over time as she discovers new apps, and figures out what does & doesn't work well on a tablet. Does she have any particular hobbies or common activities?