Mahoromatic: Automatic Maiden, Kore ga Watashi no Goshujinsama Recommendations
Both are about Maids living-in with their employer, and both are ecchi.
Both series have a lot in common in a general sense. A young guy gets young maid/s to work for him. Both series were done by Gainax. Also both have a similar sense of humor. While it takes the similar concept as He is My Master, Mahoromatic does ever thing better. Mahoromatic has a far better story, is funnier, and ecchier.