What to do with domains.

[Electra]

Whats the best way of letting go domains? Is it private sale or auction, or just dumping them? I've been cleaning out a bunch of domains that we collected but I know I'll never do projects on them now. I've just been not renewing them but it will eventually come down to domains that are somewhat good..or really good..but I still might never use them. Do you guys hang on to all your domains regardless? Seems a shame to have purchased them and then never used them only to not renew them years later..very wasteful