I came across this great post by Tanya Costigan of Bowties and Butterflies Event planning, and I wanted to share it with you. They have gathered all the best apps for IPhone, Ipad and Android. Here are few, but you should Check it out for the complete list.
Wedding Party
This free app allows a private place for you and your guests to share memories. Once your guests have signed up for the app, they can take pictures and upload them. This means that you end up with tons of pictures, that you might not have otherwise gotten, taken from your guests point of view.

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Noeeva Wedding Playlist
This app (free) allows you to create your wedding day playlist (or playlist
for any event for that matter). You can upload your own music, or browse
music right from the app, including what's trending now. It gives you the option to export the playlist as well.

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myPANTONE X-Ref
This
app isn't marketed for weddings, but comes in handy for them! Pantone
is the trendsetter in wedding colors. Check out the spectrum of endless colors and get inspired for your wedding color choices with this free app.

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Perfect Wedding Guide (PWG)
Perfect
Wedding Guide (PWG) is a handy app where you can keep track of your
wedding budget, access your guest list, find vendors, find bridal shows
and local wedding deals. This is a free app chock full of wedding tools right from your phone!

partially re-posted from http://bowtiesandbutterflies.com