I've been a pretty big fan of Dividend Reinvestment Plans (DRIPs) over the years and something close to half of my invested assets are in them. For those who want to invest small amounts without having to deal with a broker, I really think these are a very good option because you can put in money in dollar rather than share denominations.
In terms of where to go for them, here are a few different websites of providers:
Shareowner Online (Wells Fargo):
Investor Service Direct (BNY Mellon):
ADR.com (JP Morgan):
There are a few others out there, but these are the ones I would start with. There are some companies that seem to do it directly such as Procter and Gamble (PG): http://www.pg.com/en_US/investors/investing_in_pg/sip.shtml
I think these are fantastic programs, but keep an eye on the fee schedules when choosing how to do your automatic investments. If the plans charge a dollar per transaction and you put $25 in a month, that doesn't make much sense. You are paying 4% transaction costs then.