You are halfway there :)
In general, NATing firewalls have two basic necessities for moving traffic between interfaces. In the strictest of senses there are many more, but the two below are the ones encountered most often. The first is the access control and the second is a translation rule. This paradigm is true for most firewalls -- even if they don't expose it in a limited GUI (SOHO/consumer firewalls/routers) -- the GUI may be doing it for you underneath. On the CLI, however, you must take care to configure access control and the translation rules.
If your example you have configured the access control side of things with an access-list. The OUTSIDE_IN access-list is bound to the outside interface in the IN direction.
Knowing that, your access-list is telling the ASA to permit TCP traffic recieved on the outside interface from any source IP/TCP port combination destined for 208.x on TCP/80, 208.x on TCP/678, and 208.x on TCP/789.
The next step (or first step depending on how you like to do things) is to create a translation rule so the traffic gets translated -- after passing an access control check of course.
In ASA 8.2 and earlier this is accomplished with the static command. Major changes to NAT were implemented in ASA 8.3 and later -- so the following does not apply to 8.3 and up.
- 188.8.131.52/TCP/80 <-> 192.168.1.100/TCP/80
- 184.108.40.206/TCP/678 <-> 192.168.1.101/TCP/678
- 220.127.116.11/TCP/789 <-> 192.168.1.102/TCP/789
- 192.168.1.0/24 on the inside interface
I have filled in the remaining octets of the external IP address with 1's to show clearly that we will be Port Address Translating (PAT), specifically static PAT, on a single external IP address. This is opposed to the more traditional static NAT where each internal IP would have its own unique external IP.
static (inside,outside) tcp 18.104.22.168 80 192.168.1.100 80 netmask 255.255.255.255
static (inside,outside) tcp 22.214.171.124 678 192.168.1.101 678 netmask 255.255.255.255
static (inside,outside) tcp 126.96.36.199 789 192.168.1.102 789 netmask 255.255.255.255
In general static PAT should be avoided as it is the ugliest type of NAT from both a management and technical standpoint. If you need to expose many internal servers to the Internet, the cleanest way to make it happen is with traditional static NAT -- where each server would have its own external IP.
ASA 7.2 Command Reference
ASA 7.2 Command Reference static Command