On our first trip to Italy, we discovered Murano glass (and somehow managed to safely bring home a handful of lovely pieces). Ever since, we've always gravitated towards colorful glass displays...
We love how a large grouping of beautiful glass vases never looks cluttered because of its transparent quality. Light bounces off a colorful display easily, making the collection the focal point of any room. It's an easy way to add color to a space (without making a commitment). Not to mention glass can be found rather inexpensively at local thrift stores--which makes collecting it that much more delightful.
(Images: 1. Dave and Melanie's Craftsman Color, 2, 5, Inside Out: Versailles on the Upper West Side?, 3. Look!: Vintage Glass at The SFDC, 4. Windowsill Collections)