You can punch it in the phone, then use call/hangup quickly. In the last dialled, the number will have a name matched to it.
Also, live searching while dialing has been suggested and not everyone agreed - most people dial to avoid contacts and listing them to onlookers is less than fun. You can search for the thread if you wish to participate.
It already has one, there's a nickname field (add a field). It's included in searches. Also, it's picked up from other address books that have nicknames, like Google Contacts and IM when you start using those protocols. Am I missing something? Is there stuff you want that the "Nickname" field doesn't provide?