You may want to research the 'octane boosters'. Most of them do very little if anything. Read the label closely if you don't believe it, they actually do tell you...
Here is a link to one, the rest are all very similar.
http://www.allbatterysalesandservice.com/browse.cfm/4,4006.html
See where it mentions it raises it 3 point? A 'point' is considered 1/10 of a whole number, so if you have 12 gallons of gas at 87, dumping in this entire thing will raise it to 87.3. (most are rated at 12 gallons of gas) If you have 24 gallons, you get a whopping 87.15 instead of regular old crappy 87.00.
The ABSOLUTE best octane booster is e85, period. Its between 105 and 115 octane, and will mix in a relatively linear fashion. The tricky part is you can't generally run a nice mix of 100 octane without other engine/fuel mods. The second best octane booster is naphtha. I forgot the effective octane concentration, but IIRC it was about 20:1 to get 97 octane.
(I've done TONS of research on this subject, I tune the computer systems on my turbocharged car often with my own custom map/tuning information. Currently I'm set up to burn a 60/40 mix of 91 octane gasoline and e85, which is about 97 octane.)