Placing a paper under review on my website?
The answer depends critically on your field: you need to talk to your advisor and find out what the general policy is.  Three examples along the spectrum of radically different possibilities:


In mathematics, theoretical physics and theoretical computer science, papers under review are circulated publicly long before being published.  This practice is a key motivator behind arXiv.
On the more empirical/applied side of computer science, making a paper under review publicly available wouldn't be a problem except in case of double-blind review, but would generally be considered rather gauche.  Circulating privately in advance, on the other hand, is quite accepted.
Many biology journals aim to tightly control the timing and release of information. In many cases, posting a paper under review could actually be considered prior publication, and result in the paper being disqualified as a submission and automatically rejected.


Find out which are the practices of your field and follow them.