The list of appropriate orchids is far too long to even begin. There are an estimated 30000 orchid species and half as many hybrids.

What you want to do is look for plants that can deal with consistent conditions year around. You will want to stick to miniature plants so they have room to develop and flower properly. Warm growing Pleurothallids do well, as do many Bulbophyllums. It really depends on your experience level and the conditions you can provide. Low light orchids are a much better choice if you actually want to see blooms.

Here are some fairly easy to find Pleurothallids that would be good candidates.

Pleurothallis brighamii
Pleurothallis grobyi
Pleurothallis tribuloides

Try using the search feature at Andy's Orchids website.

Mike,

Thanks for the response. How about these
BULBOPHYLLUM lobbii
BULBOPHYLLUM vaginatum
or any other Bulbo.

Thanks,
Namnhi

Bulbophyllum lobbii will get too big for most terrariums but Bulbophyllum vaginatum would be a very good candidate. I have lots of experience with Bulbophyllums so if you do some searching on the net and have any questions just ask.

There are many other genera of orchids that will do very well so I would recommend looking for flowers that you like and then figure out if there are miniature versions of those types. One thing I can't stress enough is that you pay attention to light requirements because many orchids will never flower in the terrarium and many also have flower spikes that are too long and make them poor candidates as well.

This is a good site that has a list of vendors in the U.S. Take a look at Andy's Orchids and Oak Hill Gardens because they have lots of great plants at good prices. Feel free to ask if you have any questions about other plants and I will try to help you with figuring out their needs.

This link is good for cross refrencing the light requirments etc. of orchid species but there are no hybrids listed. The requirments of each plant are shown with symbols and there ia a general description of the plant and flowers along with photos. http://www.orchidspecies.com/

Here is a link that might be useful: The orchid house

How about Den. jenkensii? I have a tiny one that I'm about to put in my terrarium. I also have a Ludisia discolor and Macodes petola in my tank. Some other orchids that I think would like high humidity and do well mounted would be Dendrobium prenticei(might be a little misspelled) and Platystele stenostachya. The Platystele gets little tiny orange flowers with two tiny black dots that look like eyes. I've heard of people growing Dracula and related genera but wouldn't recommend them from personal experience. There are some small Chysis species out there that might like the humidity of a terrarium.

Dendrobium jenkensii would be a good sized for use in terrariums but it requires a dry winter rest to flower. All of the others you mentioned would do very well but Draculas need fairly specific conditions leaning towards cool with good airflow and lots of pure water. Chysis species will get far too large and also need a drier winter but they are wonderful plants never the less.

Thanks guys
I order BULBOPHYLLUM vaginatum and Pleurothallis grobyi from Oakhill. I should have it today.
Thanks again.
NamNhi

Have you checked
T & C Terrariums ?

I have had success with Haraell odorata(retrocalla) in a 55 gallon viv. It has bloomed for me twice since I got it in January. The key is ventiliation which I provide with computer fans.
Here is the link to some of my pics
http://www.orchidboard.com/community/gallery/showphoto.php?photo=630&limit=recent
Haave a look around the website while you are there.

Here is a link that might be useful: My gallery

Did anyone mention ghost orchids? I would think they would do well in a dart frog tank especially, since they have all glass tops and little to no ventillation.

Polyrrhiza lindenii is not an easy orchid to grow and they are far more likely to die off than grow especially if you don't have previous orchid experience. There are several people on the Gardenweb orchid forum that grow them and one growers plant is in double spike right now.

The thing with ghost orchids is that that like damp conditions, low air movement and that have no leaves so they photosynthesize through their roots. The roots have to be exposed to light for this to happen so mounting is a given. The best results I have seen have been achieved with the use of commercial mychorhizal fungi products to allow the orchid to develop a relationship with the fungi and boost its growth and tolerance of conditions in culture.

There are other leafless orchids that are easier to grow if you are interested take a look at the Chiloschista species.