Isa Browns are ok for the first year, but they're bred to lay like crazy for their first year and then drop off with their laying later on. They're not great long-term layers.
Silkies are ok, but quite fragile so not particularly hardy, if that's a characteristic that you're looking for. They are super cute, and pretty good layers for a bantam sized hen.
Australorps are probably the best layers that I know of, and they're really tough and hardy chooks. Quite good all-round.
My preference is for Araucanas, which are tough as guts and lay blue/green eggs! Good layers, but not as good as Australorps. They're full of personality, too.
A lot of people get Pekin bantams as backyard hens, which aren't bad layers and they're also pretty tough. Very very cute.
Have a look at some other breeds too - Wyandottes (beautiful and layers), Sussex (good layers), Rhode Island Red, Leghorns.
I'm not sure about the rules on posting links to other forums, but I've received heaps of help from www.backyardpoultry.com which has a forum attached, as well as a noticeboard where you can advertise for eggs/chooks and find advertisements from sellers.