Here's a nice paper that looked at post-processing methods of increasing the strength of Nylon SLS parts, they tried annealing the samples for different times at different temperatures as well as infusing them with Thompson's waterseal and superglue.
Their results showed about a 57% increase in (impact) strength with annealing at 183 C for 3 hours, but the parts distorted since they were only 1 degree below the melt temperature. At 180 C (3 hrs) they saw about a 42% increase in strength, which still seems pretty significant. That having been said, you would need a pretty accurate oven to heat them to 180 C as going just a few degrees higher would melt the part, and going lower the effect drops off pretty quickly.
As for infusing parts, believe it or not they saw more benefit from Thompson's than superglue. But even the Thompson's only made about a 14% improvement in strength. Superglue showed little to no improvement, which was surprising to me.
You can see the paper here -->
http://sffsymposium.engr.utexas.edu/Manuscripts/2003/2003-57-Zarringhalam.pdf
I have some pretty accurate ovens at work, I may actually try annealing some parts at 180 and see what happens. I may also try picking up some Thompson's