Another new field type in the FieldTypes shared source project: introducing Text List, a field for maintaining lists of predefined items with autocomplete and drag & drop reordering. Most people should be familiar with it by now.

Selected items and adding a new item, autocomplete:

Drag & drop reordering:

Text List field should be a good fit for maintaining a list of tags, email addresses and such:

While looking fairly different, it is a typical Sitecore list field, storing list of selected item IDs and requiring source to prefetch a list of items to select from.

More details on FieldTypes wiki.

It took a bit of work, and some features could be missing - please report any issues.