I've got 6,894 Cubs cards from 30 different brands listed on a spreadsheet. A random number generator picked five cards, one each from the past several decades.
1950's / 1960's Topps 1968 #13 Chuck Hartenstein This card is from series one of the 1968 set. It's easy to identify cards from the first series because the "wicker" pattern is much wider apart than in the rest of the set. Hartenstein was coming off of a nice season in 1967, going 9-5 out of the pen. He flopped in '68, though, falling to 2-4 with a 4.54 ERA. Over the winter he was traded to the Pirates.
1970's Kelloggs 1979 #1 Bruce Sutter The Kelloggs cards in the late '70's were skinnier than the earlier ones, but the 3D feature was still unique enough to make you want to eat a lot of cereal. The 1979 season was Sutter's best as a Cub, as he won the Cy Young Award and was the winning pitcher in the All Star game. His 37 saves tied the league record.
1980's Fleer 1986 #378 Ryne Sandberg This card has a nice shot of Ryno following through on his swing. Though an All Star and Gold Glove winner, Sandberg saw his home run, RBIs and batting average all drop in 1986.
1990's Fleer 1996 #U242 Sammy Sosa Encore This card is from Fleer's update set. SInce Sammy already had a card in the base set, this is his Encore card. Sammy's numbers from '96 were pretty decent, 40 HR and 100 RBIs. They're even more impressive when you consider that those are from 124 games. In game 124 he was hit in the hand by a pitch, breaking his pisiforme bone and ending his season. He was leading the NL in homers at the time of his injury.
2000's Upper Deck 2002 #312 Tom Gordon After missing all of the 2000 season following elbow surgery, the Cubs picked him up off of the scrap heap and he was pretty good, saving 27 games after joining the team off of the DL on May 1. In 2002, a spring shoulder injury shelved him until July, and after only 19 appearances over the next two months, he was traded to the Astros. Flash's success with the Cubs was just a flash in the pan.