Some ways to display mathematics elegantly:
  1. MathML rendering by LaTeX syntax: LaTeXMathML
  2. External LaTeX Rendering: CodeCogs' LaTeX Equation Editor
The following examples show the rendering difference. Try to turn off/on JavaScript to see the original code.
MathML Examples:
  1. The infinite strings $\Sigma^{\infty}$ is given by the projective limit of finite strings, i.e. $\Sigma^{\infty} = \lim_{\leftarrow} \Sigma^{n}$
  2. $\displaystyle{\bot \sqsubseteq \phi (\bot) \sqsubseteq \phi^{2}(\bot) \sqsubseteq \cdots}$ gives a least fixpoint if $\phi$ is order-preserving over $\mathbf{dcpo}$.
External LaTeX Rendering Examples: 

  1. \xymatrix{
X \ar[r] \ar[d] & FX \ar[r] \ar[d] & F^{2}X \ar[r] \ar[d] & \dots \\
Y \ar[r] & FY \ar[r] & F^{2}Y \ar[r] & \dots  }
  2. Naturality of Five Snake
    \xymatrix{
&&&A_2\ar[rr]\ar[dd]|\hole^(.36){a_2}&&B_2\ar[rr]\ar[dd]|\hole^(.36){b_2}&&C_2\ar[rr]\ar[dd]|\hole^(.36){c_2}&&0\\
&&A_1\ar[rr]\ar[dd]^(.36){a_1}\ar[ur]&&B_1\ar[rr]\ar[dd]^(.36){b_1}\ar[ur]&&C_1\ar[rr]\ar[dd]^(.36){c_1}\ar[ur]&&0\\
&0\ar[rr]|\hole&&A'_2\ar[rr]|\hole&&B'_2\ar[rr]|\hole&&C'_2&&\\
0\ar[rr]&&A'_1\ar[rr]\ar[ur]&&B'_1\ar[rr]\ar[ur]&&C'_1\ar[ur]&&
}
Use MathML as much as possible, since we can zoom in or out, search, apply CSS styles and so on.
For diagrams or complicated graphs which cannot be rendered by MathML, it makes sense to use external LaTeX render, however.