You can group SharePoint 2010 services using the SharePoint 2010 object model and a high level point of view.
The following services can be grouped into Configuration Services:
- Microsoft SharePoint Foundation Incoming E-Mail
- Microsoft SharePoint Foundation Subscription Settings Service
- Microsoft SharePoint Foundation Workflow Timer Service
- Diagnostics (Tracing)
- Outgoing Mail
- Usage
Configuration Services are services holding configuration settings but can’t be grouped into Windows services, Web services or IIS Web services.
The last 3 ones can’t be turned on or off but can be configured using Central Administration.
Note: Screenshots below are taken from the server, but should be the same in Foundation.
Relevant posts
Resources
What is it?
Quotes taken from Background: Service Entities in Microsoft SharePoint Foundation.
Microsoft SharePoint Foundation Incoming E-Mail
“This service typically runs on only one application server and enables SharePoint Foundation sites to receive e-mail.
Doing so can make it possible to let users add items to a list by e-mail.”

Microsoft SharePoint Foundation Subscription Settings Service
“This service supports site subscriptions.” Aha…
Note: Ok this one isn’t necessary for alerts or RSS feeds regarding to Services architecture planning (SharePoint Foundation 2010): “Provides multi-tenant functionality for service applications. Tracks subscription IDs and settings for services that are deployed in partitioned mode. Deployed through Windows PowerShell only.”
If this is interesting for you Spencer Harbar has some articles about that subject: Rational Guide to Multi Tenancy with SharePoint 2010
Microsoft SharePoint Foundation Workflow Timer Service
“This service supplements the main Timer service […] with configuration settings for timed workflow events.”
Here are some screenshots:


Diagnostics (Tracing)
“This service supports tracing for the Unified Logging Service (ULS). It runs on all front-end Web servers and application servers.”

Configuration of diagnostic logging allows now the reset the changes to default.
Outgoing Mail
“This service that typically runs on only one application server and it enables SharePoint Foundation to have e-mail functionality such as e-mail alerts when a list has changed.”

Usage
“This service encapsulates settings for usage logging and processing in a SharePoint Foundation deployment.”
Note: These pictures are taken from the server but the described link is also available in foundation.

The files are usually logged to the logs folder in the 14 hive.
Availability
The mentioned configuration services are included in all of the SharePoint 2010 products.
Summary
The Subscription Settings Service was a little bit confusing since I thought it’s about alerts and RSS feeds which seems to be wrong.