Runescape Market Watch

The Grand Exchange advanced the Runescape market into a new era. From medieval type of a market we came to capitalistic (or some say socialistic) market. Either way, efficiency of the market place clearly has improved and amount of goods transferred through it increased. With improved efficiency and liquidity came a need for structuring and price trends tracking. And while price trends have always been there ("rares market" participants would surely know), only The Grand Exchange made it virtually a necessity for merchants. As a result we can see various market indexes and researches appearing in the Runescape community. Two of them I know about are:
1) Runescape Wiki's Common Trade Index (updated daily, current prices but no analytics)
2) TruthScape Weighted Index of RuneScape Prices (TWIRP) (updated weekly, therefore prices may be a few days off, but contains tons of analytics)

I found both places to be very useful for my merchanting decisions, so, yes, I highly recommend both.
I also added a special Runescape Market Watch page to Runewise, where you can quickly find a summary for both indexes, which I believe would be a good starting page for a Runescape merchant.

P.S. If you know about other Runescape market indexes projects out there, please, let me know in the comments.