I like to type with my device on my lap. I got into the habit thanks to the wireless keyboard that I've got for my laptop, and I wanted to recreate that experience with the iPad.
Step 1: find a BT keyboard. I got a good deal on a refurbished Logitech BT keyboard case, and I like using it. However, the only drawback to using the iPad on my lap as is, with this configuration, is that it's a bit small to balance well on my lap. (I like to sit in what could be described as a half-lotus position.)
But I ran across a lap desk on eBay that I thought I would give a try. It's another Logitech item (I have no financial stake in their company, lol), their N315 lap desk. It's got an extremely non-skid surface, and is an excellent companion for the keyboard case. Once I put that iPad/keyboard onto the lap desk, I know that my device is going NOwhere unless I pick it up! No need to worry about my device sliding off the lap desk!
Do some price checking on both these items, if you're interested in buying one or both of them, as their prices vary widely.