These are mainly brandable domains - so, your buyer will often be an end user, looking to brand their product/service....Or, a reseller that thinks a name has good odds of someone wanting it.
The (very few) names that are 'just right' for something can be very valuable to the right buyer.
Here are some sales of 'i' domains:
iReport.com - $750,000 - Jan 2008 - (DNJournal)
iSearch.com - $300,000 - August 2008 - Pte Sale
iGuide.com - $100,000 - July 2009 - Afternic DLS (DNJournal)
iPets.com - $75,000 - June 2008 - Afternic
iPal.com - $59,000 - August 2009 - Sedo (DNJournal)
iBanks.com - $38,000 - April 2008 - Sedo
iMingle.com - $30,000 - Dec 2009 - Sedo
iLicense.com - $28,000 - March 2009 - Sedo
iUS.com - $25,000 - Jan 2009 - Aftermarket
ii.org - $22,895 - April 2007 - Moniker
iRent.com - $20,000 - Sept 2009 - AfternicDSL (DNJournal)
iGossip.com - $18,000 - Oct 2008 - Sedo
iMode.com - $17,001 - Jan 2009 – Snapnames
iArt.com - $16,694 - May 2008 - Namejet
iTrust.com - $13,100 - June 2009 - Namejet (DNJournal)
iTeam.com - $10,650 - March 2007 - Snapnames
iVow.com - $10,215 - July 2009 - GoDaddy (DNJournal)
iQuotes.com - $10,140 - July 2008 - Sedo
iReplay.com - $10,000 - Oct 2007 – Sedo
iFeed.com - $9,900 - Dec 2009 - Sedo
iDonate.com - $9,000 - Dec 2007 - Afternic
iPoolTables.com - $7,000 - August 2009 - Sedo (DNJournal)
iSexy.com - $5000 - Dec 2009 - Sedo
.