Hell-Volhard-Zelinski?
Krapcho decarboxylation?
Corey-Fuchs alkyne synthesis?
There are lots of great name reactions out there, but I want to know your favorite! It can be because it has an awesome name or because it's really useful, just tell us why!
I'll start us off:
I pick the Claisen rearrangement. It's a ridiculously powerful reaction for transferring stereochemical information, but Claisen thought that the version we use the most today was really more of a curiousity; he was much more interested in the reaction with phenyl allyl ethers that gave allylated phenol type products. Despite tons and tons of research, a highly effective, general enantioselective catalyst for the reaction has yet to be identified. Whoever does find one will probably make some serious $ off of it!