Lately I've been experimenting with the Meditation on Voidness from the Cula-Sunnata Sutta. I've also taught it as a guided meditation to groups and people seem to get something out of it so long as they don't let themselves get lost in speculative thought (trying to figure it out)
This is a wonderful practise which has received very little attention. Here are instructions in a nut-shell.
The meditation proceeds through a series of contemplations. The whole trick of making it work is to remember that nothing new is added at any stage. On the contrary, each stage is a successive subtraction. You advance through the stages by a process of selective non-attention.
1 - Begin with contemplation of village - this is a simple mindfulness exercise. Be aware of your surroundings, as they actually are, the room, the furnishings, any other people. Don't analyze or judge or compare. Just hold the surroundings in mindful awareness. When this is established, extend your imagination beyond the visible surroundings to take in the immediate area, the street etc., extending only as wide as is comfortable for you.
2 - Next, move on to contemplation of forest. (In scriptural useage village is a word for the whole human constructed world, forest for the natural environment.) Simply remove all human constructions from the previous mind-field and focus only on the natural world, the plants and trees especially. Remember, selective non-attention. You don't add anything, you subtract. The "forest" was a part of the first contemplation, now you make it the foreground by non-attention to "village."
3 - Next, by selective non-attention to the living world you move on to contemplation of earth. By non-attention to the living growth, become aware of the wide earth-element underlying things. Be aware in the imagination of the hills and valleys, bowls for any nearby lakes, etc. Allow your field of imaginative awareness to expand until you are holding the whole globe of this planet in awareness.
4 - Next, by non-attention to earth one should become aware of space. At first, this will be the space occupied by the earth. Removing the earth from awareness, space becomes the foreground. (Again note it was present all along - we subtract and do not add) Space by it's nature has no boundaries, so the idea of an earth-sized area should quickly dissolve into boundlessness. Hold the awareness of boundless space.
5 - Your consciousness is now filling boundless space. Okay, stop noticing space and only pay attention to the boundlessness of consciousness. Mind without limit.
6 - In the next contemplation, we stop paying attention to boundless mind and let the mind rest in nothingness.
7 - If you're able to take it this far, eventually even nothingness starts to seem "busy". In the next step we remove the concept of nothingness from our field of awareness and rest in the field called "neither-perception-nor-nonperception." Don't try to figure it out. The name is meaningless really, it's what's left when you remove nothingness.
After holding this for a while, return to the body with some mindful breathing before getting up. Good luck with this if you are inspired to try it; let me know if it works for you.