I agree httpclient is something of a standard - but I guess you are looking for options so...
Restlet provides a http client specially designed for interactong with Restful web services.
Example code:
Client client = new Client(Protocol.HTTP);
Request r = new Request();
r.setResourceRef("http://127.0.0.1:8182/sample");
r.setMethod(Method.GET);
r.getClientInfo().getAcceptedMediaTypes().add(new Preference<MediaType>(MediaType.TEXT_XML));
client.handle(r).getEntity().write(System.out);
See http://www.restlet.org/ for more details