I've seen on some Ricer sites that sell the colored ones also sell something referred to as "halogen" ones that are supposedly bright.  I have not tried them, I fear if they are truly a higher wattage they might get to hot (ours get pretty dam hot as is).  I chose to get a maplight mirror and sit farther back (an option on the 2doors, 4 door guys are screwed).
Also you might want to try getting replacement lenses.  Depending on your budget they arent really that much and I noticed an improvement.  Mine were all yellowed and burnt from the bulb I guess.  The new ones are much clearer and the light is whiter.
Also a couple tips for improving the lighting on our cars.  Some people have deleted the Check panel and added one there.  Some have put a small one like the glvoe box light in the panel covering the sunroof motor (considering this myself).  These should help a lot since its not the light that is the problem but its location behind the drivers head. 
![Angry    [:(!] [:(!]](/images/smilies/icon_smile_angry.gif) 
 
Also in the trunk if you have an 86-87 car with the thinner lights you might be able to find some early bulb holders that had a clear cutout for the parking light so it shined into the trunk. Mine has this and it helps. 
I also took a salvaged glove box light and affixed it to the top center of the dense cardboard material at the back of the trunk.  That helped a lot, just rant some 18/2 security wire up to the trunk switch.
Good cheap mods.
Im also considering seeing if something could be put in the footwells, because its a bitch to find something if you dropped it.