We do not have any specific limits on IP addresses. One IPv4 address is assigned per cloud server by default. More can be assigned easily by opening a support ticket. We require valid justification for new IP addresses. A valid reason for needing extra IP addresses is for SSL. An invalid reason would be SEO. We have to abide by ARIN guidelines especially with the shortage of IPv4.
IPv6 addresses will be assigned to all servers soon, every server gets a /64 of IPv6 which allows you to create a near unlimited number of addresses for your server. (As of July 12th)