Founders Bloc provides resources to entrepreneurs and freelancers, as well as a platform for them to connect and support one another.
They redid their product a couple years ago, and I think it's really smooth and nice--I'm very impressed with it.
Stripe offers a very simple, clean integration with the space management tool we use.
Lucidchart is great for designing user flows
We also accept a lot of checks. Nothing formal here--there are only two of us.