I've put two requests on Response Source, for two stories with lots of buzzwords (green IT, cloud, SaaS) which has led to a flood of responses. Some very much what I was asking for, some rather broader, some really quite off topic, most as requested by email, a couple by phone (hint: this does not make me more likely to use that pitch). There's usually an expectation with these pitch services that journalists will respond to the pitches that they definitely want to pursue and not feel obliged to tell everyone else that they were flooded with more responses than they can possibly consider. I'd love to be able to respond to everyone individually but with pieces like this, if I get that many responses I have the choice between writing the article and spending the time thanking everyone I can't fit in this time. If I don't get back to you on this or another pitch request, please take this as thanks for responding, an explanation that I had too many responses to deal with and an apology that I haven't been able to respond personally.