As well as the overloads of the Load method which take a file path, there are overloads which take a Stream or a TextReader as the source:
File path:
void Load(string)
void Load(string, bool)
void Load(string, Encoding)
void Load(string, Encoding, bool)
void Load(string, Encoding, bool, int)
Stream:
void Load(Stream)
void Load(Stream, bool)
void Load(Stream, Encoding)
void Load(Stream, Encoding, bool)
void Load(Stream, Encoding, bool, int)
void Load(TextReader)
There's also a LoadHtml method which accepts a string containing the HTML to load.
"These people looked deep within my soul and assigned me a number based on the order in which I joined." - Homer