- Carry great weights (djinn: up to 6,000; efreet: up to 10,000. Call it 1,000 gp/HD, but djinn get a -1 HD penalty because they are aerial beings)
- Create permanent soft or organic items
- Create temporary metallic items (gold lasts 1 day, softer metals last longer, harder metals last a shorter time)
- Create illusions, no concentration needed
- Turn invisible
In addition to these generic "magic giant" powers, djinn have the powers of the air (turn into whirlwind, become gaseous) and efreet have powers of the flame (Wall of Fire, immolate themselves.) You could generalize the "magic giant" template and come up with other varieties: add these to Invisible Stalkers to get a simpler "generic demon"; give these powers to the rakshasha and ogre-mage; give an efreet volcano powers and call him a volcano god.