Heycraig!: get alerts when Craigslist has what you're looking for
To use Heycraig!, just put in a search term and your email address, and specify your local Craiglist site. Heycraig! could benefit from a multi-city option, but Craiglist is notorious for cracking down on sites that offer systemwide functionality, so it's unlikely to happen. If you're looking across more than one local network, you'll have to take a little time to set up more than one search. Some advanced search options to narrow down the results on Heycraig! would also be helpful, particularly to specify a neighborhood or area in larger cities. If you're casting a wide net, though, Heycraig! could prove very useful.