I use the following on several 2.5 gallon tanks:
with this light:
Look online for Petsmart coupons. I got two for 15.00 with free shipping, but that was last year. I like this light bulb best because it is longer than a CFL.
I grow moss, riccia, dwarf hairgrass, java fern, anubias and crypts. It's not perfect, but works well for me. It's a pretty clean looking little set-up. The only problem is if you use a HOB filter, the glass lid doesn't fit perfectly. You either have to cut it, or cut a thick piece of plexiglass. Thin plexiglass will warp, but is still usable.