Only a very few fallback nodes are persistent over time, and compiled (hardcoded) into the bitcoin client itself.

https://en.bitcoin.it/wiki/Fallback_Nodes is a viable method of bootstrapping.  We'll call that "forum bootstrapping" or "wiki bootstrapping", where one must manually search for a list of nodes, in order to bootstrap onto the network.

I think DNS bootstrapping would be the most efficient:  a simple DNS lookup to bootstrap.bitcoin.org would work like this:

• Community members post their nameserver (NS) records for bootstrap.bitcoin.org on the forum.  Presumably this list does not change often
• Each member runs a DNS server, independently of anyone else, that retrieves addresses from bitcoin's addr.dat database, randomly selects "fresh" P2P nodes, and stores these in A records or SRV records.
• When bootstrapping, the bitcoin client performs a standard DNS lookup for bootstrap.bitcoin.org

That would be very, very fast.  Much faster than IRC.  This is similar to how BitTorrent DHT bootstrapping occurs.

The only issue is trust (rogue DNS servers), but this issue also exists with the IRC server, which is a Single Point of Failure (SPOF) for both trust and general reliability.