I bought a six pack of GE “General Purpose” (as opposed to “Cool natural light”) compact florescent light bulbs [item number: 71285, bulb model number FLE 26HT3/2/SW 26watt, equivalent to 100watt incandescent light bulbs] at Wallmart and was pleasantly surprised. In addition to having a warm color temperature (no harsh blue-white light here!) the bulbs turned on practically instantly! No more waiting for a half second for the CF bulb to flicker while “charging up”.

I needed a few more, so I bought a two pack of “General Purpose” GE bulbs [item number 72877] at Wallmart a week later. Unfortunately, these bulbs were slightly different, and did not have the immediate “instant-on” ability of the bulbs that came in the six-pack. The “slow startup” bulbs had the following serial/model number: Helical 26 W 102VAC 60Hz 400mA FLE 26HT2/2/XL/SW
Physically, their helical glass coil is just slightly smaller than the “instant-on” versions.

Both types of GE 100 watt bulbs are slightly too large for some fixtures. I have found an alternative 23W (75W equivalent) CF bulb by Sylvania (the CF23EL/Micromini 3000K) that also has very nice “instant-on” behavior, and is a good inch shorter than the GE 26W bulbs. (As it’s a 3000K color temp, it is also very “normal” looking.)

At Kroger I found a rare 3-way CF bulb (50/100/150 equivalent) from GE with model number “FLE32HLX/2/D/SW”. Unfortunately, it had a full second delay before it produced any light at all.

To summarize, the following model number CF bulbs turn on instantly:
Sylvania 23 watt: CF23EL/Micromini 3000K
GE 26 watt: FLE 26HT3/2/SW

And if you want an instant-on experience, you should avoid the following:
GE: FLE 26HT2/2/XL/SW
GE: FLE 32HLX/2/D/SW