Answer questions in online forums.
Point people to online resources, including some of my websites. Among other things, I blog about homelessness as a lightweight means to empower the powerless.
Pass out cards with URLs to homeless people and tell them where they can get internet access and electricity. When I was first homeless, it was news to me that you can get free Wi-Fi at the library.
Give away cheap wiped smart phones or tablets to homeless individuals.
Contribute to online resources that curate information, such as where to find Wi-Fi.
Give homeless people Starbucks gift cards so they can get a coffee and get online and plugged in.