Excel: Drop-down list with multiple entries in a single cell

Is there anyway, I can create a drop down list that allows users to choose items from a list and place them into a single cell with comma separation (e.g. Rome, New York, Rio Di Janero) If I could limit it to one item per cell, a simple drop down data validation list would work, but I need to limit entry to 1 cell/column. Any suggestions would be much appreciated.

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This thread is current as of March 24, 2012.

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