This one may be micro-enterprise.
Doing your laundry is a basic requirement wen you travel for more than few days. Laundry charges are very high at most hotels, sometimes more than the cost of the garment itself. You have a choice to buy new pair of garment but then carrying them is a constraint. In fact if convenient and reasonable laundry services are available, most travelers would travel far lighter than they do now.
Idea is to put a small washing machine at a convenient place, where people can go and do their own laundry for a per load cost. A dryer would be an additional help as would be an ironing board. The total cost of equipment can be around 20-25 K and the minimum can be 10 K. The constraints that you need to figure out is that of space and water availability.
My hunch is that people would be willing to pay something like Rs 100-150 per load of washing, but this of course needs to be validated. Idea is small and can be easily tested a couple of locations. Long term travelers would love this.