I'll give you an idea that I've done in the past consulting. Create a web-based reservation system for small tour operators. Part CMS, part inventory system, these operators need to create bookings for passengers, reduce inventory, generate invoices, update their website (that's the CMS part) with new inventory, sales, deals etc.

You'll make much more than $5K / month if you can pull that off. Heck, I'll send about 5 companies your way on Day 1.