I came up with the following changes from reading Backup and Restoration Strategies from the manual. Most of them are typos, with a couple of suggestions thrown in.

Block Level Methods

I think this section could use an introduction saying what needs to be backed up are the dbpath data files. This isn't actually stated anywhere, so when you read the content that follows, the question that constantly comes to mind is, "But what actually needs to be backed up?"

Database Dump with mongodump

1st paragraph:

• "The mongodump utility performs a live backup the data" -> "The mongodump utility performs a live backup of the data" ("of" missing)

• "or part of a collection using of query,)" -> "or part of a collection using a query)" (replace "of" with "a", remove comma before bracket)

• "in a in the current directory" -> "in the current directory" (remove "in a")

Paragraph straight after first example command:

• "This command creates a dump in of the database" -> "This command creates a dump of the database" (remove "in")

Two paragraphs later:

• "the location to your MongoDB instance's database files" -> "the location of your MongoDB instance's database files" (replace "to" with "of")

Replica Sets (at bottom of page)

First paragraph:

• "When you unlock the database, the slave will catch master or primary node." -> "When you unlock the database, the slave will catch up to the master or primary node." (presumably this was the intent)

Finally, this page does not mention that in 2.0.x mongodump/mongorestore does not restoring indexes (SERVER-1311), and that it is fixed in 2.2. Could that be added?