My most recent batch I tried almond extract, but I'm not getting the nuttiness I expected. I've heard using different malts can get different nutty flavors but how can I get a rich nutty flavor?
A rich nutty flavor comes from a combination of a little roast/toasted malt and some biscuity strong malty notes.
You get roasted/toasted from things like toasted malt, pale chocolate or chocolate malt (used in moderation). You can get the malt/biscuit thing from munich malts, and biscuit/victory malt. (Granted biscuit and munich don't taste the same, but I lumped them in together for the purpose of this discussion)
It depends on the style beer you are making though on how much and which malts you chose. If we are talking about Nut Brown then chocolate, victory and munich is just what you need.
Other malts to consider may be special roast (not special B) and melanoidin malt.
These are the malts I have worked with and gotten the most nutty flavor out of in things like brown ales, dark Amber, Porter or stout.
Victory, Biscuit, Amber, Brown, Chocolate, Special Roast, Roasted Wheat, some Light Munichs.
If I'm aiming for nutty, I tend to go for a combination of Victory and Chocolate or Roasted Barley for a nice dry, biscuity, nutty flavor.
Want to rock a delicious nut brown? Try this:
I would recommend taking a look at this list of popular ingredients that I just found: http://www.beertools.com/html/ingredients.php?view=grains
American Caramel 60°L seems to give you that nutty flavor you're looking for.
Also to get a better idea of how the nutty flavor is achieved, you might want to check out: http://www.byo.com/stories/wizard/article/section/121-mr-wizard/1618-what-ingredients-produce-the-nutty-flavor-in-a-nut-brown-ale