BarNotes puts an encyclopedia of classic cocktails and new innovations right at your fingertips, together with users’ stories and comments. (Free, iOS only)
Quilt uses photos and videos that guests post in real-time to create an instantly archived scrapbook of the big night. (Free, iOS or Android)
Invy streamlines the task of picking a party date. Post the dates that’ll work for you, and invitees weigh in to arrive at a consensus choice. ($2, iOS only)
Songza, a music streaming site, can serve as a “discount DJ.” The app offers various “expertly arranged” party mixes, cataloged by theme. (Free, iOS or Android)
Seedio connects the music libraries of your guests’ phones, allowing users to create a “group-approved party playlist” that’ll stream through the phones. ($3, iOS only)