"RiverCity.dev" can be a great domain with a more understated theme. Here are some ideas:

1. **Urban Planning Insights:** Curate data and insights on urban planning and development for riverfront cities. Highlight best practices, case studies, and lessons learned to foster sustainable growth along riverfronts.

2. **Riverfront Revitalization:** Showcase initiatives and projects aimed at revitalizing riverfront areas. Highlight the transformation of these spaces into vibrant cultural hubs, recreational zones, and attractive destinations for residents and tourists alike.

3. **Community Engagement Platform:** Build an online platform for riverfront communities to connect, share updates, and discuss ideas for improving their city's riverfront areas. Encourage residents, businesses, and local leaders to collaborate on enhancing the urban experience.

4. **River City Histories:** Create a digital repository of historical information, stories, and photos related to riverfront cities. Celebrate their rich heritage and show how they've evolved over time.

5. **Local Businesses and Events:** Feature businesses, restaurants, and events along riverfront areas. Highlight the unique offerings and experiences that make these River Cities stand out.

6. **Sustainability Initiatives:** Focus on sustainability and environmental efforts in River Cities. Feature initiatives related to clean energy, waste reduction, and responsible development along riverfronts.

While "RiverCity.dev" might not have the flashiest concept, it can serve as a valuable resource and community hub for cities that take pride in their riverfront locations.