Data Science Project Ideas
I would try to analyze and solve one or more of the problems published on Kaggle Competitions. Note that the competitions are grouped by their expected complexity, from 101 (bottom of the list) to Research and Featured (top of the list). A color-coded vertical band is a visual guideline for grouping. You can assess time you could spend on a project by adjusting the expected length of corresponding competition, based on your skills and experience.
A number of data science project ideas can be found by browsing Coursolve webpage.
If you have skills and desire to work on a real data science project, focused on social impacts, visit DataKind projects page. More projects with social impacts focus can be found at Data Science for Social Good webpage.
Science Project Ideas page at My NASA Data site looks like another place to visit for inspiration.
If you would like to use open data, this long list of applications on Data.gov can provide you with some interesting data science project ideas.