Perhaps these are the cheapest and easiest layout baseboards you can find

In a word (two words actually): folding tables. The pre-built kind, which you can get through Amazon and lots of other places. Adhere your pink/blue foam or other subroadbed/scenery base to the tabletop, and you've got an inexpensive and (probably, choose wisely) lightweight layout that folds up when not in use.

I've noticed there are some common sizes which seem particularly well suited for N scale, including 30" X 72", 2' X 4', and 34" square. There are even some round folding tables, but they're pricier.

Use Flickr for model railroad inspiration

Here's one of those seemingly basic ideas that can turn out to be invaluable. Flickr, the photo indexing and sharing Web site, has interest groups called "Pools" (where many users' photos can be combined and displayed together) which can be a terrific source for model railroad scenery ideas. Here's a few you can check out:

http://www.flickr.com/groups/16506306@N00/pool/

http://www.flickr.com/groups/indecay/pool/

http://www.flickr.com/groups/id_trees/pool/

http://www.flickr.com/groups/81809473@N00/pool/

http://www.flickr.com/groups/railroadart/pool/

A quick n' "dirt"-y plowed field

This works well in HO or N scale ...

Start with a piece of scrap corduroy fabric, cut to the desired size of your field. It should be an earth color, tan or brown (or else gold or green). Study a photo of the type of field you're trying to recreate; often the fabric will look right as is ... otherwise:

Paint some glue into the "crevices" of the corduroy and sprinkle on some dirt or earth ground cover; let dry and shake off the excess.

Paint glue on the remaining "tall" parts, and sprinkle on green or yellow fine ground foam. Let dry and shake off the excess. Glue the piece down and that's it!

Keep your eyes open for miscellaneous small things that can be used as scenery

I'm doing a design at the moment that incorporates a rather unusual industry: a landscape supply company, the kind with lots of fountains and statuary piled around outside. I was scratching my head trying to think what I would use for all this outside merchandise, and got the answer recently when browsing a craft store: glass or ceramic beads. I will just select the appropriate sizes and shapes, and paint and weather them.

The experience reminded me that all kinds of random bits can be pressed into service on a layout. Look around you, see any ideas?