New CCK field types
The Content Construction Kit (CCK) is one of the most useful frameworks in Drupal. CCK allows fields to be added to node types, thus extending the usefulness of a node type. Fields consist of an underlying data type (string, integer, date...), a widget (the UI), and a formatter (for presenting the data). A field can also be more complex, such as a file field, an image field, or a computed field.
If the CCK interests you, your Summer of Code project could be to create a new field type. Do your research in advance and make sure that the field you are proposing doesn't exist, and that it is really suitable for being a CCK field.
Darrel O'Pry has written a tutorial on creating CCK fields. Lullabot has published an article explaining the inner workings of CCK. Read these to help formulate your ideas.
NOTE: This is purposefully open-ended.
My goal is for creative students to propose their own original CCK field ideas in their applications. Bonus points will be given for those who demonstrate an understanding of the potential for different widgets, formatters, Views integration, and other nice things like field-specific actions (via Actions module).

This is a pretty ambiguous
This is a pretty ambiguous proposal at the moment. I think we need ideas about WHAT field types could be created.
I have one idea: a Google map (and/or other similar mapping API) selector & a 'location' field to define a location (by lat and longitude). The idea comes from this screenshot on flickr and a need for a current project. there may be avenues for integration into the location module.
Needs more thought and development this proposal -- obviously.
Prospective students encouraged to come up with their own.
My goal in writing this proposal in such an ambiguous state is to encourage people to apply with their own original ideas for CCK fields.
- Robert Douglass
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Lullabot | my Drupal book
Event CCK field
I'd love to see event integration into CCK. Similar to Date field, but Event. I would imagine a widget similar to Google Calendar add event view (just the "When" part). It should include options like:
Multimedia Field
It would be good to modify the multimedia field that already exists, to allow video and audio to play embedded in the page, as Youtube or Goggle Vids.
Rosamunda
Buenos Aires | Argentina
www.ligadelconsorcista.org
Wouldn't an event field
Wouldn't an event field actually be an event node with those various date fields? Also, I was under the impression that these features are currently being worked on in the date field.
--Ryan
www.ryancross.com
www.jamescrossinc.com
Well, it won't be a "field",
Well, it won't be a "field", more like a widget, but not a node. You should be able to add event data to any node - exactly what CCK allows to do with its fields. I'm aware that event module can be attached to any node as well, but I thought making it a CCK field would be more consistent and more flexible. I didn't know that there were plans to enable all of the above feature in date field. Can someone point me to the discussion thread / news on that.
This is not a proposal
Please clean it up with some direction and feasible goals, like http://drupal.org/node/121112.
Actually, it is a suggestion for student's own creativity
This is specifically to be in line with the advice given here: http://code.google.com/p/google-summer-of-code/wiki/AdviceforMentors
The goal of this proposal is to set a desired direction for students to be creative; finding new and interesting CCK fields to implement, with the corresponding Views integration (and Actions integration?) is, in my opinion, a rich source of potential projects.
- Robert Douglass
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Lullabot | my Drupal book
periodic table
I would like to implement a periodic-table-field, where the node creater could select one or more elements. its for an mineral-databse.