A interesting one Ive come across recently are technical founders that run a solutions company where a retired exec of a large company in a particular industry is an advisor/investor and assisting with leads.

Screams of corruption but in practice not really so. The exec knows there industry well, finds out where they struggle to find solutions, passes info down to the company. The company then creates specialised software to deal with it and joins a tender. As they have a trusted person on board it assists in getting in the door. Also the competition will usually not be very technically advanced.

Revenue streams are variable from rev-share to cost + maintenance. In a lot of cases the same solutions can be sold to others within the same vertical or outside it. Anecdotal but founders Ive met in this area seem far more successful than those on a more traditional VC / bootstrapping tract. Perhaps because a lot of the hard part of enterprise sales is solved by the advisor.

This may be an asia-specific style of business, not sure.