The CIDR finder box in the CheckUser tool is a useful tool; as a CU I often find the IP range of an ISP through WHOIS and copy-and-paste it into this box to convert into a CIDR range (for running subsequent checks, blocking the IP range, etc). However, most WHOIS websites return values like xxx.xxx.xxx.xxx - xxx.xxx.xxx.xxx and the - (space minus space) part prevents the CIDR tool from calculating the range. I have to go and manually remove the spaces for it to work.