If you are interested in the area of drug discovery, then the following four web servers related to drug design may be helpful for your work.

PharmMapper: PharmMapper Server is an updated integrated pharmacophore matching platform with statistial method for potential target identification.

ChemMapper: ChemMapper is a free web server for computational drug discovery based on the concept that compounds sharing high 3D similarities may have relatively similar target association profile.

SiteMapper: SiteMapper is a free web server for binding site comparison based on residue match and deviation minimization.

iDrug: iDrug is an online interactive drug discovery and design platform which can perform protein binding sites detection, pharmacophore searching, potential target candidates identification and 3D similarity calculation