How to combine the values of the same field in several rows into one string?

How to combine the values of the same field in several rows into one string?

Imagine the following two tables:
create table MainTable (
MainId integer not null, -- This is the index
Data varchar(100) not null
)
create table OtherTable (
MainId integer not null, -- MainId, Name combined are the index.
Name varchar(100) not null,
Status tinyint not null
)
Now I want to select all the rows from MainTable, while combining all the
rows that match each MainId from OtherTable into a single field in the
result set.
Imagine the data:
MainTable:
1, 'Hi'
2, 'What'
OtherTable:
1, 'Fish', 1
1, 'Horse', 0
2, 'Fish', 0
I want a result set like this:
MainId, Data, Others
1, 'Hi', 'Fish=1,Horse=0'
2, 'What', 'Fish=0'
What is the most elegant way to do this?