gistfile1.r

## read data
ll <- readLines(textConnection('28/03/13        FACTURE CARTE           DU 240313 PHOTOBOX SARTROUVILLE CARTE            -30
25/03/13        2EME TIERS SUR FACTURE  DE 180 EUR DU 240113 CAROLL INTL PARI            -60
25/03/13        RETRAIT DAB             24/03/13 11H15 166936 BNP PARIBAS PARIS          -200.50
18/03/13        PRELEVEMENT             TRESOR PUBLIC 94 IMPOT NUM 005002 ECH 18         -500'))
## convert data to a data.frame
dat <- do.call(rbind,strsplit(gsub('[ ]{2,}','|',ll),'\\|'))
## name columns 
colnames(dat) <- c('date','category','desc','amount')
dat <- as.data.frame(dat)
## type variables
dat$date   <- as.Date(dat$date,'%d/%m/%y')
dat$amount <- as.numeric(as.character(dat$amount))
dat$desc <- as.character(dat$desc)

## you can aggegate per date for example 
library(plyr)
dat.daily <- ddply(dat,.(date),summarise,amount = sum(amount))
library(ggplot2)
ggplot(dat.daily)+
  geom_line(aes(x=date,y=amount))
## you can compute amout per category 
table(dat$amount,dat$category)