I have not used a grow light for years - before CFL and LED bulbs existed. I now want to get a desktop grow light to help a couple small plants in my office get more helpful light. I will probably put it on a timer so it shines on the plants during the night.
Is there a specific LED or CFL grow light desk lamp you can recommend? 
Yes, I can:
https://www.led-tech.de/en/High-Power-LEDs-Osram/Osram-Modules/Grow-Modul-with-7x-OSRAM-SSL-80-LT-2499_206_209.html
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https://www.led-tech.de/en/High-Power-Supply/Coolers/NanoLED-7050-Mechatronix-Cooler-LT-2436_106_114.html?cross=2436
Those China-Grow-COBs aren’t too bad, but they aren’t very effective, so this module is much better.
A lot of plants rely and use the different cycles of dark and light over the year.
Giving them light at night can confuse them, but it depends on the plant you are using it for if this is a problem. Say the plant we Dutchies are famous for is very sensitive to the proper day.night cycle and the only way to grow such a plant with lights during the night is to fake shorter days (put 1 cycle in 12 hours) very tricky.
Then in most plants green is not used, hence the green color. Do get lights at the other end of the spectrum for optimum watts to growth benefit.
I got myself a big E27 multiple led light with a red purple color to get our veggies going.
Did not test it bu start around Jan 15th.
Only hickup for me is that I want to use our elevator (nice at centre of house, dark with window doors covered so for me ideal to trick the veggies into thinking time passed fast by the 12 hour trick) but even though we did only use it to get heavy stuff up and down my wife really hates the idea to render it not usable as elevator for 3 months so I am looking for another place since well the wife will always win right.
I will check later for the light I bought and post it in this thread
Google search for led grow lights brings up lots of reviews on them.
430, 460, 630 and 660 are 4 peaks wavelength of growth spectrum for maximum chlorophyll A and B production.
Blue light is good for photosynthesis; and help to induce Chlorophyll and Carotenoid, which are necessary for healthy leaves.
660 nanometersis the peak wavelength for photosynthesis. Red light is best for blooming and fruits.
OK i tried to fin the one I bought, sorry, too man orders at too many shops
It looked a bt like this one
click
but we are in \eu with 230V and E27 is normal here, I got some things laying aroun to fit it in without modding.
If you really want to encourage growth, check out the AeroGarden models. Just got one for my wife for Christmas (talk about a great trade!) 
Many models available and the bigger ones will let you grow some plants to maturity indoors, year around.
What driver would I need to power 2 of those modules with a 24 volt battery that occasionally sees 29 volts?