Well, the Christmas Check List cum Planner App can have following features:
Budget Tracking and Grouping
For creating Check List of different items (for e.g. Gifts, Foods & Drinks, Decorations, etc.) to be shopped; and keeping track of budget with cost summary.
For creating Groups like Family, Friends, Colleagues, etc. and add people from your Mobile contacts
For adding photos or pictures related with person you want to gift (this could be an optional feature)
For adding multiple gifts for a single person (if required)
For tracking status of gifts, i.e. to be purchased, shipping, received, wrapped, etc.
For Making a note of gift ideas
A timer and countdown to Christmas will not only inform users about the days left but will also create a sense of urgency among users who may otherwise land themselves in a situation like Last Minute Christmas Shopping which can be expensive and exhausting.
Christmas Greeting Card Creation (Can be offered as Paid Feature)
To allow users to create a beautiful Christmas Greeting Card in case they have forgotten or cannot buy expensive gifts and presents for everyone. This will not only save them money but will also help them to dodge an embarrassing situation.
App can feature tips for users who may want to refer and gain from them. Tips like putting Christmas lights on timer & buying energy-efficient light bulbs to cut on electricity costs, getting part-time Christmas jobs like gift wrapping, etc. to make extra money to spend on Christmas and beyond.
Gift Ideas (Can be offered as Paid Feature)
People are always short of great gift ideas particularly on Christmas, so if an app compiles one such list of ideas for presents, it could matter a lot for users.
The above mentioned list of features is not comprehensive and can have other possible features like Security, Pre-Loaded List of Stores and Items, Ability to Add Items using Barcode Scanner, Social Media Sharing and Email Sending from App, etc.