1) Mobile phones. Super cliche, but they use mobile phones in every aspect of their lives now, and it has made a tremendous difference. Something that used to require an hour bus ride to the nearest city and then waiting in line for an hour, ruining a days worth of work in the fields can now be accomplished in 5 minutes via SMS.
Airtel (one of the largest mobile providers in the world, one of the biggest companies in India) has made a tremendous amount of money by focusing not on ARPU (Avg. Revenue per user) like every other mobile company, but rather focusing on how much profit they can make per minute sold... they are happy to serve tons of farmers that only use their phone for 100 minutes a month (~$2 a month). If it was not profitable for Airtel, the poor would never have access to cellphones, something that has DRASTICALLY upgraded their lives. Nokia sells amazing phones tailored to that market for $20... they have radios, flashlights, and batteries that last a week (all crucial to rural India), and Nokia is able to maintain fantastic margins on those products. Airtel has an ARPU of $4 (contrast to US carriers ARPU of ~$55)... yet they have a $30Bn market cap
I actually co-wrote a case on this topic with professor CK Prahalad (the founder of base of the pyramid thought - you should read up on him. if this topic interests you at all read his books, particularly "the fortune at the base of the pyramid" http://en.wikipedia.org/wiki/C._K._Prahalad) If you're interested in reading my case (http://www.globalens.com/casedetail.aspx?cid=1428834) give me a shout.
2) Clean water. A lot of villages don't have it. There are both for-profit and non-profits trying to tackle this situation, but regardless they've found that the only way to scalably get clean water to the masses is to charge for it... to "profit on the backs of the poor" I co-wrote a case on that topic here: http://www.globalens.com/casedetail.aspx?cid=1428987