Does the Nikon D3000 have a battery grip available?

Yes, it does. They sell one on Amazon.

Includes batteries- http://www.amazon.com/Opteka-Battery-Vertical-exte...

No batteries included- http://www.amazon.com/Opteka-Battery-Vertical-Shut...

Here is a picture of what it looks like when it is on the D3000...

http://www.flickr.com/photos/katmunge/4143216321/

I listed 2 links below that may be of help, one is to Nikon's website page for the D3000 and you can see if anything is listed there, I did not see a grip listed.

The other link could be more helpful, it is to nikonian.org and to a page in the discussion forums area where someone is asking about a battery grip for the D3000 and a string of responses.

Hope this helps.

Good luck.

Mark