A second course in modular forms I was wondering what would be a suitable project/ reading to do as a second outing in Modular Forms. I have read Serre's book "A course in arithmetic" in a Topics course last semester, right upto (and including) Hecke operators. 
Suggestions I have received till now are mostly geared towards reading Diamond-Shruman "A first course in modular forms". But as I understand, this is a serious graduate level textbook and would be too dense for my final semester Undergraduate project. 
Left to myself, I would happily explore more of congruence subgroups and higher level modular forms from Koblitz' book "Introduction to elliptic curves and modular forms" and supplement it with problems from Murty's "Problems in the theory of Modular forms". Does this sound like a good plan to you ? Please help with more suggestions, especially in a project flavor (even a small side project would do). 
Thanks in advance
EDIT: Knowing my background in number theory and related areas might help:
Algebra- Abstract algebra, Field and Galois theory, Representations of finite groups, Commutative algebra
Algebraic number theory- Number fields, number rings, Ideal Class group, Dirichlet's Unit theorem, Quadratic reciprocity, p-adic fields and rings, Hensels lemma, quadratic forms
Analytic number theory- Reimann-Zeta function, L-functions, Dirichlet's theorem on AP's, Modular forms
Analysis- Complex Analysis, Fourier analysis on the circle and finite Fourier, Measure theory
 A: A lot depends on what most interests you about modular forms. Do you care more about the analytic aspects or algebraic aspects? Do you want to learn about modular forms for their own sake, or are you interested in where they fit in the wider world of number theory and their applications to, for example, Fermat's last theorem?
I haven't read Koblitz, but my (possibly flawed) understanding is that it is slightly more analytic, for example looking at things like half weight modular forms. It is quite a gentle introduction. Zagier's book is similar in this respect. 
Based on your background, you stand a good chance with Diamond and Shurman. It is not actually a book about modular forms; rather it is an introduction to the modularity theorem (formerly the Taniyama-Shimura conjecture). As such, there is plenty you can skip and still come away with a detailed knowledge of modular forms as well as a good grasp of the ideas that go into the proof of Fermat's last theorem. 
Chapters 1 and 2 are the introduction to modular forms over congruence subgroups that you're looking for. 
Chapter 3 gives dimension formulas for spaces of modular forms and can happily be skimmed. I would skip chapter 4 and study chapter 5 which is about Hecke operators. The key point is that the modular forms which are eigenvalues for all the Hecke operators form an orthogonal basis for the space of modular forms. 
Chapters 6-8 are tough, but if you're willing to take on trust that we can attach Galois representations to modular eigenforms, then you can readily skip to chapter 9 (you'll have to skip some of the proofs in $\S$9.5), which is a gentle introduction to Galois representations and their relation to Fermat's last theorem and the modularity theorem.
