SharePoint 2010 Service Account

Account name	Role	Domain rights	Local SharePoint Server rights needed	SQL rights needed
sp_install	Used to install SharePoint binaries.	Domain User	Local administrator on all SharePoint boxes	dbcreator and securityadmin SQL roles
sp_farm	Farm account. Used for Windows Timer Service, Central Admin and User Profile service	Domain User	Local Admin during UPS provisioning, log on locally right	None
sp_webapp	App pool id for content web apps	Domain User	None	None
sp_serviceapps	Service app pool id	Domain User	None	None, unless using Office Web Apps. Them must give access to content databases manually
sp_search	Search process id	Domain User	None	None
sp_content	Account used to crawl content	Domain User	None	None
sp_userprofile	Account used by the User Profile services to access Active Directory	Must have Replicating Change permissions to AD. Must be given in BOTH ADUC and ADSIEDIT. If domain is Windows 2003 or early, must also be a member of the "Pre-Windows 2000" built-in group.	None	None
sp_superuser	Cache account	Domain User	Web application Policy Full Control Web application super account setting	None
sp_superreader	Cache account	Domain User	Web application Policy Full read Web application super reader account setting	None

See http://technet.microsoft.com/en-us/library/ee721049.aspx 

Again, these are just recommendations. You may end up using more accounts if you have multiple application pools, for instance. Your particular farm may require different accounts.