The Custom Field Template plugin extends the functionality of custom fields.

The Custom Field Template plugin adds the default custom fields on the Write Post/Page. The template format is almost same as the one of the rc:custom_field_gui plugin. The difference is following.

• You can set any number of the custom field templates and switch the templates when you write/edit the post/page.
• This plugin does not use the ini file for the template but set it in the option page of the plugin.
• Support for TinyMCE in the textarea.
• Support for media buttons in the textarea. - requires at least 2.5.
• Support for multiple fields with the same key.
• Support for hideKey and label options.
• You can see the full option list in the setting page of the plugin.
• You can customize the design of custom field template with css.
• You can replace custom keys by labels.
• You can use wpautop function.
• You can use PHP codes in order to set values. (experimental, code = 0)
• You can set an access user level in each field. (level = 1)
• Supprt for inserting custom field values into tags automatically. (insertTag = true)
• Adds [cft] Shortcode to display the custom field template. (only shows the attributes which have output = true)
• Adds template instruction sections.
• Adds the value label option for the case that values are diffrent from viewed values. (valueLabel = apples # oranges # bananas)
• Adds the blank option. (blank = true)
• Adds the break type. Set CSS of '#cft div'. (type = break)
• Adds [cft] Shortcode Format.
• Adds the sort option. (sort = asc, sort = desc, sort = order)
• Support for Quick Edit of custom fields. (tinyMCE and mediaButton are not supported yet)
• Support for the custom field search. (only shows the attributes which have search = true.)
• Adds [cftsearch] Shortcode Format. (under development)
• Adds PHP codes for the output value. (outputCode = 0)
• Adds PHP codes before saving the values. (editCode = 0)
• Adds the save functionality.
• Adds the class option. (class = text)
• Adds the auto hook of the_content(). (experimental)
• You can use the HTML Editor in the textarea. (htmlEditor = true)
• Adds the box title replacement option.
• Adds the select option of the post type.
• Adds the value count option.
• Adds the option to use the shortcode in the widhet.
• Adds the attributes of JavaScript Event Handlers. (onclick = alert('ok');)
• Adds the Initialize button.
• Adds the attributes of before and after text. (before = blah, after = blah)
• Adds the export and import functionality.
• Adds the style attribute. (style = color:#FF0000;)
• Adds the maxlength attribute. (maxlength = 10)
• Adds the attributes of multiple fields. (multiple = true, startNum = 5, endNum = 10,multipleButton = true)
• Adds the attributes of the date picker in text type. (date = true, dateFirstDayOfWeek = 0, dateFormat = yyyy/mm/dd)
• Adds the filter of page template file names (Thanks, Joel Pittet).
• Adds the attribute of shortCode in order to output the shortcode filtered values. (shortCode = true)
• Adds the attribute of outputNone in case there is no data to output. (outputNone = No Data)
• Adds the attribute of singleList attribute in order to output with <ul><li> if the value is single. ex) singleList = true
• Adds the file upload type. (type = file)
• Adds the fieldset type. (type = fieldset_open, type = fieldset_close)
• Adds the option to deploy the box in each template.

Source from: http://wordpress.org/plugins/custom-field-template/