YES:Tuberous begonias Park's Whopper (12")
YES: Celosia Amigo Mahogany Red (6")
YES: Celosia Fireglow (20", but will cut back)
** IF YOU CUT BACK, YOU CUT OFF FLOWERS, TOO.

YES: Snapdragon Cascadia hybrid mix (8")
YES: Snapdragon Night and Day (18")
YES: Salvia Hotline (10-12")
YES: Dichondra Silver Falls
YES: Caladium Florida Sweetheart (from bulbs)
** LATTER GET VERY TALL, HOWEVER.

I don't know about the rest.
The only thing to keep in mind is that these plants should be space generously, or you get very poor plants. This is especially true under grow lights. Also some plants, such as the salvia and celosia large root balls and should be given large pots. Tuberous begonias should be given wide pots (not necerssarily deep, but wide) as they grow. A 10" pot for a mature begonia is not unreasonable.

Kdjoergensen,
Thanks for the tips. More shelving space is obviously going to be needed, as I'm sure you're right about space. So far as cutting back, my plan is to remove the central leaf when the plant is quite young; from the hours I've spent on the forums, it was my impression this would encourage thicker branching. Do you think I misunderstood? Oh, some good news- the husband of a co-worker says he'll be glad to take anything I don't have room for. What a relief! Some of these seed packets have 50 or 100 seeds, and even though I don't plan to plant them all, if past experience is any indication, there'll be lots and lots of nice seedlings for adoption.
Thanks again.
Becky