Suggest move to Code Review?
I recently wanted to flag a post as off-topic and point to Code Review. But there is not a Code Review option in the off-topic section. Maybe it's good to include it.
The migration path to Code Review is a fairly specific one, from a topical standpoint. Unlike the migration paths for SuperUser and ServerFault, questions posted to Stack Overflow that might be on-topic for Code Review are almost always on-topic for Stack Overflow also. All other things being equal, we favor leaving a question on the site in which it was originally asked, if it is already on-topic there.
The Programmers.SE migration path is probably the best reason we don't open up a path to Code Review. People still don't fully understand this migration path; in many cases, questions migrated to Programmers.SE are migrated in error, either because they already have problems such as "Not Constructive," or because Programmers.SE is still regarded as a haven for "soft" questions.
A migration path to Code Review could have similar problems. Many people don't know this, but CodeReview.SE only accepts questions containing working code.
In truth, most questions should not be migrated at all. Only a narrow category of fairly high-quality questions that just happened to be asked on the wrong site (a rare breed, indeed) are good candidates for migration. For this reason, the number of target sites available to ordinary users for migrating questions is kept intentionally small.
In short, it is much easier to make a decision to move a question from SO to SU or SF than it is to move one to Code Review. If you do see one, cast a moderator flag requesting migration to Code Review.