dSploit is great and packs tons of features and has wrappers for nmap (and other tools like hydra) and can also search the national vulnerability database. It also has many MITM attacks and login crackers(hydra). But its not available on the Play Store though. But APK can be downloaded here
Another tool worth mentioning is Interceptor-ng. Which is basically like/is wireshark for your Android device. Its available on the Play Store
Network Discovery is also pretty good and light; and can scan for hosts and open ports. Its available on the Play Store.
G-Mon is a powerful wardriving scanner and GSM / CDMA / EVDO / UMTS and LTE Netmonitor. And is great for scoping out access points. Its available on the Play Store.
WiFiKill is a "wifi jammer"/DoS tool which can deauthenticate an entire network (you need to be connected to it; just in case your wondering) or a single device. Its not available on the Play Store but can be downloaded here.
bcmon is a tool(experimental) which allows monitor mode on Android devices which has the Broadcom chipset. I've never used this tool and hence can't offer much of an opinion on it. More info can be found here.