RE: limitfreerelay:
Agreed, that's better. I think we should start soft-coding the amount that is considered "free" instead of hard-coding CENT, and make the default less than 0.0001 BTC.
Separate subjects:
The entire transaction memory pool should be size-limited, with lower-priority transactions dropped.
I agree with Steve-- free transactions are a HUGE selling point, and I think rational miners should realize that their bitcoins will be more valuable if there are more users. And there will be more users if "free transactions" is a feature. I think we can come up with a solution where "normal" transactions are free, but spam or abnormally complicated transactions (yes, like those bitpenny rewards pooled mining participants are currently getting once a day) "require" a fee (where "require" is really "if you don't include a fee your transaction will probably never be confirmed.")
And finally... we've got a problem right now; lets think about what fix(es) move us in the right direction quickly, or think about fixes that will solve the current problem (that we may need to undo/rework later).