I just bought Osfoora HD for the iPad and I'm lovin' it! Yes, it's another Twitter client, but this has one slick user interface and an impressive list of features. I was jumping around my 3 Twitter accounts and having a blast in almost no time. It works well with Instapaper and has all the whistles and bells anyone should need without being complex or intrusive -- it's put a smile on my face, that's for sure. Best of all it's on sale now for $1.99 for a limited time.
Check it out. Osfoora HD