Oricon took a break again, so the sales numbers are available only for the top 5.
Here is the weekly manga sales ranking top 30 for March 2nd - 8th.

*1, 1,194,145 1,194,145 One Piece vol.53
*2, *,228,056 *,228,056 Bakuman vol.2
*3, *,186,491 *,420,287 Pluto vol.7
*4, *,161,988 *,161,988 Eyeshield 21 vol.34
*5, *,135,583 *,135,583 JoJo's Bizarre Adventure Part 7: Steel Ball Run vol.17
*6, *,*72,019 *,148,820 Team Medical Dragon vol.20
*7, *,*62,746 *,*62,746 La Corda d'Oro vol.12
*8, *,*62,479 *,*62,479 Otogi Moyou Ayanishiki vol.5
*9, *,*62,348 *,*62,348 Shaman King vol.26 Complete Edition
10, *,*53,928 *,158,458 Kyou, Koi wo Hajimemasu vol.5

11, *,*51,716 *,*51,716 Sket Dance vol.7
12, *,*48,068 *,*48,068 Sengoku Tenshouki vol.4
13, *,*47,556 *,108,392 To Aru Kagaku no Rail Gun vol.3
14, *,*47,092 *,*47,092 Shaman King vol.25 Complete Edition
15, *,*46,654 *,*46,654 Drop vol.6
16, *,*42,788 *,*42,788 Toshokan Sensou: Love & War vol.3
17, *,*41,975 *,*88,699 Gaku vol.9
18, *,*41,351 *,*41,351 Psyren vol.5
19, *,*41,210 *,*41,210 Beauty Honey vol.3
20, *,*40,292 *,*40,292 Akagami no Shirayuki Hime vol.3

21, *,*40,176 *,*40,176 Sengoku Gaiden vol.2
22, *,*39,123 *,119,482 B.O.D.Y. vol.15
23, *,*38,991 *,*82,292 Himitsu vol.6
24, *,*38,619 *,393,702 xxxHOLiC vol.14
25, *,*35,132 *,*35,132 The Kurosagi Corpse Delivery Service vol.11
26, *,*33,809 *,*99,018 Switch Girl!! vol.8
27, *,*33,566 *,106,344 Keroro Gunsou vol.18
28, *,*31,110 *,*66,260 Toradora! vol.2
29, *,*29,877 *,*29,877 Shinjuku Swan vol.17
30, *,*29,544 *,*74,236 Ichigo Mashimaro vol.6

Additional info:
According to Japan Magazine Association, the sales of the three major shounen manga magazines in 2008 are as follows:

WSJ showed a slight increase but the sales of the other two dropped.

Last week's ranking: Japan's Weekly Manga Ranking For Feb 23 - Mar 1
Source: Bunkyodo
Source: J-magazine
Source: Oricon Comic Ranking