This site provides detailed intelligence information on IP addresses. As well as identifying the location and registered organisation of each IP address, it performs real-time lookups against a series of databases to identify potential red flags against an address, including:

It also supports providing lists of IP addresses - in any format - which will all be looked up simultaneously.

This tool was designed for use within the DFIR field, where looking up a series of IP addresses and determining their potential threat is vital. It has way more uses than this, however, so feel free to use it however you wish!